Abdomen & Small Parts · 75 cards 0 of 75 rated

Sonographer in the Making

Abdomen & Small Parts Flashcards

Informational, double sided. The most important facts on the card, an anatomy illustration and an ultrasound image on each, and a QR to the digital practice questions. No questions printed on the card. Each topic opens with its normal card or cards, anatomy, function, labs, sonographic appearance, and scanning, then moves into the pathology.

Everything authored so far is on this page, 75 cards in total. The first 57 are the printed set across your eleven topics, in the order of your list. The last 18 are the four topics you said could stay digital only, contrast agents, ultrasound guided intervention, emergent procedures, and the transplant patient. Under every card there is a one to five scale and a comment box. Rate a card from cut it to must keep, and write whatever you want cut, added or reworded. You can also highlight any text on a card and press Comment on this, and the note will be filed against those exact words. Everything saves as you go and it is all here when you come back. Anatomy and ultrasound images are shown as labeled slots where the real figures are not placed yet. Card size and QR targets are still to be set.

Vascular System

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Card 1  ·  Vascular System: Aorta & IVC
Front
SITM
VASCULAR
Anatomy
IllustrationAbdominal aorta with celiac trunk, SMA, renal arteries, IMA, and iliac bifurcation
Abdominal aorta and branch order

Course

  • Retroperitoneal structure lying anterior and slightly left of the spine
  • Continuation of the thoracic aorta, extending from the diaphragm to the common iliac artery bifurcation
  • Bifurcates at roughly the level of the umbilicus (near the fourth lumbar vertebra) into the right and left common iliac arteries
  • Tapers in diameter as it travels distally

Branches in order

  • Celiac trunk (first main visceral branch; gives rise to the splenic, common hepatic, and left gastric arteries)
  • Superior mesenteric artery (SMA), just inferior to the celiac trunk
  • Right and left renal arteries (right renal artery origin usually slightly superior to the left)
  • Inferior mesenteric artery (IMA)

Wall layers

  • Tunica intima (innermost, closest to flowing blood)
  • Tunica media (middle, muscular layer)
  • Tunica adventitia (outermost)
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VASCULAR
IVC & Scanning
UltrasoundTransverse image with pulsatile aorta left of spine and IVC to the right
Aorta and IVC in transverse

Inferior vena cava

  • Situated anterior to the spine and to the right of the aorta
  • Formed by the union of the common iliac veins posterior to the right common iliac artery
  • Major tributaries include the common iliac, renal, and hepatic veins (hepatic veins enter just below the diaphragm)
  • Left renal vein courses anterior to the aorta, posterior to the SMA, and enters the lateral wall of the IVC
  • Drains blood from the lower extremities and splanchnic territories into the right atrium
  • Travels a horizontal course with its proximal portion curving slightly anterior as it approaches the diaphragm

Aorta vs IVC

  • Aorta is pulsatile; IVC shows respirophasic variation and greater than 50 percent collapse with a sniff
  • Aorta lies to the left of midline; IVC lies to the right
  • IVC is thin walled and compressible; aorta is thick walled and non compressible

Scanning technique

  • Image the aorta in transverse and sagittal planes from the diaphragm to the bifurcation
  • Measure the anteroposterior diameter outer wall to outer wall, perpendicular to the vessel
  • Obtain measurements at the proximal, mid, and distal aorta and the proximal common iliac vessels
  • Normal adult male abdominal aorta is usually less than 3 cm in diameter
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Card 2  ·  Vascular System: Aortic Branches
Front
SITM
VASCULAR
Branches
IllustrationCeliac trunk dividing into splenic, common hepatic, and left gastric arteries in the seagull configuration
Celiac trunk, the seagull sign

Celiac trunk

  • The first main visceral branch, short, giving rise to three vessels: the splenic, the common hepatic, and the left gastric arteries
  • In transverse the splenic and hepatic arteries sweeping away from the trunk make the seagull sign
  • The common hepatic artery branches into the proper hepatic artery and the gastroduodenal artery
  • The median arcuate ligament of the diaphragm can compress the celiac trunk and produce a stenotic waveform

Hepatic artery variants

  • The hepatic artery is the most variable of the abdominal arteries
  • About 12 percent of people have a replaced hepatic artery arising from the superior mesenteric artery
  • Two thirds have a right hepatic artery crossing posterior to the common bile duct or right hepatic duct, while the left hepatic artery crosses anterior to the left hepatic duct
  • The right hepatic artery supplies the gallbladder through the cystic artery
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VASCULAR
Mesenteric & Renal
UltrasoundSagittal aorta with the celiac trunk and the superior mesenteric artery arising about one centimetre apart
Celiac and SMA origins in sagittal

Mesenteric arteries

  • The superior mesenteric artery arises from the anterior aortic wall roughly 1 cm inferior to the celiac trunk
  • The inferior mesenteric artery is the last major visceral branch before the bifurcation
  • An SMA to aorta angle over 15 degrees on sagittal suggests retroperitoneal adenopathy pushing the vessel forward

Renal arteries

  • Lateral branches arising just inferior to the superior mesenteric artery
  • The right renal artery is the longer vessel, coursing posterior to the IVC and anterior to the vertebral column to reach the right hilum
  • The left renal artery runs directly from the aorta into the left hilum
  • At least 30 percent of people have more than one renal artery, which is why occlusion cannot be called unless the vessel is imaged in full

Iliacs

  • The common iliac arteries arise at the aortic bifurcation near the fourth lumbar vertebra and divide into internal and external iliac arteries
Trick: Celiac then SMA then renals then IMA. The renals hide just under the SMA, which is the landmark to find them from.
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Card 3  ·  Vascular System: IVC Tributaries & Anomalies
Front
SITM
VASCULAR
IVC Tributaries
IllustrationInferior vena cava with renal veins entering laterally and hepatic veins entering just below the diaphragm
Tributaries of the inferior vena cava

Lateral tributaries

  • The renal veins are the major lateral tributaries. Five to six veins join to form each main renal vein, emerging from the hilum anterior to the renal artery
  • The left renal vein takes the longer course, passing anterior to the aorta and posterior to the superior mesenteric artery before entering the IVC
  • The right suprarenal and gonadal veins drain straight into the IVC. The left ones drain into the left renal vein first. Lumbar veins enter posteriorly

Anterior tributaries

  • The hepatic veins enter just below the diaphragm and are the last vessels to join before the right atrium
  • Hepatic veins enlarge as they approach the diaphragm and lack the bright walls that portal veins carry

Formation and course

  • Formed by the union of the common iliac veins posterior to the right common iliac artery
  • Ascends vertically through the retroperitoneum to the right of the aorta, curving slightly anterior as it pierces the diaphragm
  • That union sits at the fifth lumbar vertebra, and the vessel pierces the diaphragm at the eighth thoracic level
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VASCULAR
Abnormalities
UltrasoundEchogenic material filling the inferior vena cava lumen with absent colour filling
Luminal filling defect in the IVC

IVC abnormalities

  • Thrombus and tumour both appear as solid material in the lumen. Tumour usually expands the vessel and may show internal colour flow; bland thrombus does not
  • Renal cell carcinoma is the classic source, invading the renal vein and extending into the IVC, occasionally as far as the right atrium
  • Assess for luminal filling defects and loss of compressibility, then confirm with colour and spectral Doppler

Predisposing conditions

  • Predisposing to renal vein thrombosis: preexisting renal disease, renal cell carcinoma, a hypercoagulable state, and IVC or ovarian vein thrombus extending into the renal vein

Congenital variants

  • Duplication, left sided IVC, and azygos continuation are the variants that confuse a scan of the great vessels
  • A dilated IVC that does not vary with respiration suggests raised right heart pressure rather than a vessel abnormality
Trick: Always look at the cava and the renal veins when a renal cell carcinoma is found. The tumour reaches them far more often than the report expects.

Normal caliber

  • The normal adult IVC measures under 2.2 cm, dilating to about 2.5 cm with a Valsalva manoeuvre
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Card 4  ·  Vascular System: Portal Venous System
Front
SITM
VASCULAR
Portal System
IllustrationPortal vein formed behind the pancreas by the splenic and superior mesenteric veins, with its right and left branches in the liver
Portal venous system and its tributaries

Portal vein

  • Formed posterior to the pancreas by the union of the splenic vein and the superior mesenteric vein at about the level of L2
  • Trunk is roughly 5 to 7 cm long; it runs to the porta hepatis and divides into right and left portal veins
  • Carries blood from the intestinal tract to the liver, draining the gut from the lower esophagus to the upper anal canal, plus the pancreas, gallbladder, bile ducts, and spleen
  • Upper limit of normal for the main portal vein is about 13 mm anteroposterior; it varies with respiration

Dual blood supply

  • The liver is fed by both the portal vein and the hepatic artery
  • Portal blood is incompletely oxygenated, under 80 percent, yet supplies up to half the oxygen the hepatocytes need because its volume of flow is so large
  • The portal triad sits in a connective tissue sheath, which is what gives portal veins their bright echogenic walls
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VASCULAR
Tributaries & Findings
UltrasoundTransverse upper abdomen with the splenic vein crossing to meet the superior mesenteric vein at the portal splenic confluence
Portal splenic confluence in transverse

Splenic vein

  • Crosses the upper abdomen from the splenic hilum and is best seen in the transverse plane
  • Joins the superior mesenteric vein to form the main portal vein slightly to the right of midline

Superior mesenteric vein

  • Begins at the ileocolic junction and ascends to the right of the superior mesenteric artery
  • Passes anterior to the third part of the duodenum and posterior to the neck of the pancreas
  • Larger in caliber than the superior mesenteric artery, which arises directly off the anterior aortic wall
  • Forms the posterior border of the pancreatic neck and the anterior border of the uncinate process

Inferior mesenteric vein

  • Drains the left colon and ascends retroperitoneally along the left psoas to join the splenic vein behind the pancreas
  • Rarely identified sonographically: it is small, covered by small bowel, and has no posterior landmark to key on
Trick: Portal veins have bright walls, hepatic veins do not. Any large radicle near the porta hepatis is portal, not hepatic.
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Card 5  ·  Vascular System: Abdominal Doppler
Front
SITM
VASCULAR
Flow Analysis
IllustrationSpectral Doppler display with time on the horizontal axis, velocity on the vertical axis, and a clear window under systole
Reading the spectral display

Must Know Terms

  • Resistive index
  • Spectral broadening
  • Plug flow
  • Sample volume
  • Hepatopetal
  • Hepatofugal

What Doppler answers

  • Whether flow is present, which direction it travels, and whether it is disturbed
  • Also used for tissue characterization and waveform analysis
  • Absence of flow separates the common bile duct from the hepatic artery beside it

Resistive vs nonresistive

  • Nonresistive vessels hold a high diastolic component and feed organs needing constant perfusion: internal carotid, hepatic artery, renal artery
  • Resistive vessels have little or even reversed diastolic flow and feed organs that do not need constant supply: external carotid, iliac, brachial
  • The resistive index compares peak systole against minimum diastole to quantify impedance

Reading the display

  • Horizontal axis is time; vertical axis is Doppler shift, so velocity. Flow toward the transducer sits above baseline, flow away sits below
  • Gray scale brightness shows how many cells are moving at a given velocity
  • Plug flow: most cells moving at the same velocity across the lumen, typical of large arteries, giving a clear window under systole
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VASCULAR
Technique & Patterns
UltrasoundTriphasic hepatic vein waveform with systolic, diastolic, and atrial components crossing the baseline
Triphasic hepatic vein waveform

Technique

  • Patient fasting, respiration suspended, done as part of the routine real time exam
  • Size the sample volume to the vessel and no wider. A gate wider than the lumen picks up neighbouring structures and produces noise and ghost echoes
  • Keep the beam parallel to flow. Accuracy holds to about 60 degrees; signal falls to zero at perpendicular, so roll the patient into obliquities rather than accept that angle

Arterial patterns

  • Aorta: proximal shows a high systolic peak with low diastole; the distal aorta turns triphasic as it nears the iliacs
  • Celiac axis: spectral broadening in diastole, unchanged after meals. The splenic artery is its most turbulent branch, from tortuosity
  • SMA: highly resistive fasting, with little or no diastolic flow, turning low resistance after a meal
  • Renal artery: nonresistive, with diastolic flow usually 30 to 50 percent of peak systole

Venous patterns

  • IVC and hepatic veins cross above and below baseline, reflecting right atrial reflux and respiration. Hepatic vein flow is triphasic
  • Portal flow is continuous, low velocity, and hepatopetal
  • Lost portal landmarks, a dilated splenic vein and SMV, and porta hepatis collaterals are indirect signs of portal vein thrombosis
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Card 6  ·  Vascular System: Aortic Pathology
Front
SITM
VASCULAR
Aneurysm
Sagittal abdominal aortic aneurysm
Abdominal aortic aneurysm with mural thrombus

Must Know Terms

  • Aneurysm
  • Fusiform
  • Saccular
  • Mural thrombus
  • Infrarenal
  • Outer to outer

Definition

  • An aneurysm is a permanent localized dilation of an artery, generally 1.5 times the normal vessel diameter or more
  • Focal dilatation of the abdominal aorta
  • Sonographically diagnosed when the abdominal aorta measures greater than 3 cm in diameter
  • Approximately 85 percent are infrarenal in location
  • Most occur at the level of the umbilicus, at or near the iliac bifurcation
  • Risk factors include atherosclerosis, hypertension, smoking, connective tissue disorders such as Marfan syndrome, and family history

Morphology

  • Fusiform: symmetric, circumferential (concentric) dilatation involving the full wall; most common shape and often contains mural thrombus
  • Saccular: focal outpouching involving only part of the wall; much less common and tends not to have thrombus deposition
  • Mural thrombus usually lies along the anterior or anterolateral wall of the lumen

Measurement

  • Measure the anteroposterior diameter on a longitudinal view, outer wall to outer wall
  • Measure the aorta at three levels (proximal, mid, distal) and at any suspected wall bulges
  • Include mural thrombus in the outer to outer measurement
Trick: If the lumen looks smaller than the outer wall, you are likely seeing mural thrombus; always place calipers outer wall to outer wall, not lumen to lumen.
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VASCULAR
Dissection & IVC
UltrasoundEnlarged aorta with a linear intimal flap dividing true and false lumens
Aortic dissection with intimal flap

Aortic dissection

  • Acute aortic syndrome characterized by an enlarged aorta with an intimal flap and demonstration of flow in a true and a false lumen
  • An intimal flap or membrane may be seen within the aortic lumen, with two patent channels or a thrombosed false lumen
  • May coexist with an underlying AAA
  • Clinical presentation includes sudden onset of severe chest pain with radiation to the arms, neck, or back; syncope may be present

IVC thrombus and tumor extension

  • Renal cell carcinoma commonly invades the renal vein; gross renal vein involvement occurs in about 21 to 35 percent of large tumors
  • A subset extend into the IVC and may reach the right atrium
  • Predisposing conditions include preexisting renal disease, hypercoagulable state, and IVC or ovarian vein thrombus with extension to the renal vein
  • Sonographic appearance: solid hypoechoic material within the IVC or renal vein lumen; assess for luminal filling defects and lack of compressibility
  • Evaluate with color and spectral Doppler to confirm absent or altered flow around the filling defect
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Card 7  ·  Vascular System: Portal Hypertension & Vascular Pathology
Front
SITM
VASCULAR
Portal Hypertension
UltrasoundTangle of collateral vessels at the porta hepatis replacing the normal portal vein
Cavernous transformation of the portal vein

Portal hypertension

  • Raised portal venous pressure, most often from cirrhosis, reverses the normal direction of flow
  • Portal flow becomes hepatofugal, away from the liver, instead of hepatopetal
  • The portal vein dilates, and loses its normal respiratory variation
  • Splenomegaly and ascites accompany it
  • Defined by a portal venous pressure above 10 mmHg or a hepatic venous pressure gradient above 5 mmHg

Collaterals

  • Portosystemic collaterals open at the sites of anastomosis: the recanalized paraumbilical vein, the coronary or left gastric vein, splenorenal collaterals, and oesophageal varices
  • A recanalized paraumbilical vein in the falciform ligament, alongside the ligamentum teres, is one of the most commonly identified collaterals
  • The coronary and oesophageal veins are the dominant pathway, opening in 80 to 90 percent of patients

Portal vein thrombosis

  • Direct sign is visible thrombus in the lumen
  • Indirect signs are loss of the normal portal landmarks, dilation of the splenic vein and superior mesenteric vein, and collaterals at the porta hepatis
  • Cavernous transformation is the tangle of collaterals that replaces a chronically thrombosed portal vein
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VASCULAR
Other Vascular
UltrasoundRounded anechoic structure adjacent to an artery showing a swirling colour pattern
Pseudoaneurysm with internal swirling flow

Pseudoaneurysm

  • A false aneurysm is not lined by all three arterial layers, unlike a true aneurysm
  • Appears as a rounded fluid collection beside a vessel, with a neck connecting it to the artery
  • Colour shows a swirling yin yang pattern inside, and the neck shows a to and fro spectral waveform
  • Patients with chronic pancreatitis are particularly prone to splenic artery pseudoaneurysm

The pseudocyst trap

  • A pancreatic pseudocyst and a vascular aneurysm look very similar on grey scale
  • Apply Doppler to every pancreatic pseudocyst before calling it one

Renal vein thrombosis

  • The renal vein shows a variable waveform similar to the IVC, so absence of flow is the finding rather than an abnormal waveform
  • Evaluate the renal veins in any patient with a suspected renal tumour or obstructive lesion
Trick: Doppler is not optional on a cystic structure near a vessel. Grey scale cannot tell a pseudocyst from a pseudoaneurysm.
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Liver

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Card 8  ·  Liver: Anatomy
Front
SITM
LIVER
Anatomy
Liver illustration
Liver, anterior view

Key terms

  • Hepatocyte: liver cell performing all liver functions.
  • Falciform ligament: connects liver to diaphragm and abdominal wall; contains the ligamentum teres.
  • Ligamentum teres: remnant of the umbilical vein; bright echogenic focus; separates the medial and lateral segments of the left lobe.
  • Ligamentum venosum: separates the left lobe from the caudate lobe.
  • Main lobar fissure: boundary between right and left lobes; runs portal vein to gallbladder neck; landmark to the gallbladder.
  • Bare area: portion of liver with no peritoneal covering; against the diaphragm.

Position & lobes

  • Largest organ in the abdominal cavity; right hypochondrium, epigastrium, and left hypochondrium to the mammillary line.
  • Inferior to the diaphragm; right lobe covered by the ribs.
  • Lobes: right, left, and caudate (posterior lobe, independent vascular supply).
  • Variant: Riedel's lobe, a tongue like projection of the right lobe.
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LIVER
Vasculature
Transverse portal triad ultrasound
Portal triad, transverse: "Mickey Mouse sign"

Portal triad & blood supply

  • Portal triad: portal vein + hepatic artery + bile duct.
  • Mickey Mouse sign (transverse): portal vein is the face; hepatic artery and common bile duct are the two ears.
  • Vascular supply: portal vein 70 to 80% of blood; hepatic artery 20 to 30%, oxygenated.
  • Right lobe receives blood from the intestine; left and caudate lobes from the stomach and spleen.
  • Three hepatic veins (right, middle, left) drain into the IVC; portal vein enters at the porta hepatis.

Flow direction

  • Hepatopetal: flow toward the liver (normal portal flow).
  • Hepatofugal: flow away from the liver (normal hepatic vein flow; abnormal if portal).
Tricks: "petal" pulls toward  •  "fugitive" flees away

Embryology

  • Develops from the foregut endoderm; ligamentum teres is a remnant of the fetal umbilical vein.
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Card 9  ·  Liver: Segmental Anatomy
Front
SITM
LIVER
Lobes & Fissures
IllustrationLiver divided by the middle hepatic vein and the ascending left portal vein into functional right and left lobes
Functional division of the liver

Anatomic vs functional

  • Four anatomic lobes: right, left, quadrate, and caudate, with the falciform ligament separating right from left
  • The functional division matters more surgically. The middle hepatic vein and the ascending left portal vein divide the liver into functional right and left lobes
  • Under the functional division the falciform ligament belongs to the left lobe
  • The right lobe is about six times larger than the left

Fissures

  • The left intersegmental fissure divides the left lobe into medial and lateral segments, with the left hepatic vein running horizontally between them
  • Two fissures sit in the left lobe: the fissure for the ligamentum teres and the fissure for the ligamentum venosum
  • The main lobar fissure appears as a hyperechoic line running from the portal vein to the neck of the gallbladder
  • The right hepatic vein lies in the right intersegmental fissure and the middle hepatic vein in the main lobar fissure
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LIVER
Couinaud & Landmarks
UltrasoundTransverse liver showing the three hepatic veins converging toward the inferior vena cava
Hepatic veins as segmental boundaries

The Couinaud system

  • Divides the left lateral, right anterior, and right posterior segments into superior and inferior subsegments
  • The caudate lobe and the medial left segment are each kept as a single segment
  • Hepatic veins run between lobes and segments; portal branches run within them, which is the rule that makes segmental localization possible
  • The exception is the ascending portion of the left portal vein, which runs in the left intersegmental fissure

Caudate lobe

  • A small lobe on the posterior surface of the left lobe
  • The IVC forms its posterior border and the fissure for the ligamentum venosum its anterior border
  • Drains straight into the IVC by its own small veins, so it is spared and hypertrophies in Budd-Chiari

Capsule

  • The liver is covered by a thin connective tissue layer, Glisson capsule
  • The bare area rests directly on the diaphragm and is not covered by peritoneum
Trick: Veins between, portals within. If a vessel runs through the middle of the tissue you are naming, it is portal.
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Card 10  ·  Liver: Vasculature & Doppler
Front
SITM
LIVER
Vessels
UltrasoundThree hepatic veins draining toward the inferior vena cava near the diaphragm
Hepatic venous drainage

Telling the two systems apart

  • The best discriminator is to trace each vessel to its point of entry into the liver
  • Portal veins enter at the porta hepatis, get smaller toward the periphery, and carry bright echogenic walls from the surrounding fibrous sheath
  • Hepatic veins drain toward the diaphragm and the IVC, get larger as they approach it, and have no bright walls
  • Any large radicle near the porta hepatis is portal

The supply split

  • Portal vein carries 70 to 80 percent of the blood; the hepatic artery carries the remaining 20 to 30 percent as oxygenated blood
  • Blood perfuses the parenchyma through the hepatic sinusoids before reaching the terminal hepatic venules, which unite into the hepatic veins
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LIVER
Waveforms
UltrasoundTriphasic hepatic vein waveform beside a continuous low velocity portal waveform
Normal hepatic and portal waveforms

Normal waveforms

  • Hepatic vein: triphasic, with systolic, diastolic, and atrial components, reflecting right atrial hemodynamics
  • Portal vein: continuous, low velocity, hepatopetal, with mild respiratory variation
  • Hepatic artery: low resistance with continuous diastolic flow, because the liver is a low impedance bed
  • Normal portal vein velocity is 15 to 18 cm per second
  • The normal hepatic artery resistive index is under 0.7

What changes them

  • A hepatic vein waveform that flattens to monophasic suggests cirrhosis or a mass effect on the vessel
  • Loss of respiratory variation in the portal vein accompanies portal hypertension
  • Right heart failure exaggerates the atrial reversal component in the hepatic veins

Measurement

  • Measure the portal vein during quiet respiration with the patient supine. The upper limit of normal is about 13 mm
Trick: A monophasic hepatic vein in a liver that looks coarse is a second vote for cirrhosis, not an unrelated finding.
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Card 11  ·  Liver: Variants & Congenital
Front
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LIVER
Normal Variants
UltrasoundTongue of right lobe liver tissue extending inferiorly past the lower pole of the right kidney
Riedel lobe

Shape variants

  • Riedel lobe: a tongue like inferior extension of the right lobe, more common in women, a normal variant rather than hepatomegaly
  • The liver may be displaced inferiorly by tumour infiltration, cirrhosis, or a subphrenic abscess
  • It may be elevated by ascites, marked colonic dilation, or abdominal tumours
  • Retroperitoneal tumours tend to shift it slightly anterior
  • Situs inversus places the liver on the left, and a congenital diaphragmatic hernia or an omphalocele can carry liver tissue into the thorax or outside the abdomen

Measurement caution

  • Longitudinal length over 20 cm indicates hepatomegaly, but a Riedel lobe will breach that figure without disease
  • Assess the parenchyma for size, configuration, homogeneity, and contour together, not length alone
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LIVER
Spaces & Relations
IllustrationSubphrenic and subhepatic spaces around the liver with Morison pouch labelled
Perihepatic spaces

Perihepatic spaces

  • The subphrenic space between the liver or spleen and the diaphragm is a common site for abscess
  • The right posterior subphrenic space lies between the right lobe, the right kidney, and the right colic flexure
  • The right subhepatic space sits inferior to the right lobe and includes Morison pouch, between the posterior right lobe and the upper pole of the right kidney
  • The lesser sac lies posterior to the liver and stomach and communicates with the greater sac near the pancreatic head. It is another site for abscess

Position

  • The liver occupies almost all of the right hypochondrium, most of the epigastrium, and reaches the left hypochondrium as far as the mammillary line

Embryology

  • Develops from foregut endoderm
  • The ligamentum teres is the remnant of the fetal umbilical vein and can recanalize in portal hypertension
  • The ligamentum venosum is the remnant of the ductus venosus
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Card 12  ·  Liver: Sonographic & Clinical
Front
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LIVER
Sonographic
Right lobe echo texture ultrasound
Right lobe echo texture & measurement

Normal appearance

  • Homogeneous texture with fine, low level echoes.
  • Echogenicity: minimally hyperechoic to isoechoic vs renal cortex; hypoechoic vs spleen; pancreas equal to or slightly more echogenic than liver.
  • Portal veins have brighter (more echogenic) borders than hepatic veins (thicker collagen sheath). Ligaments and fissures appear echogenic to hyperechoic.

Measurements

  • TRV 21 to 22.5 cm; height 13 to 17.5 cm; AP depth 10 to 12.5 cm; SAG about 15.5 cm; portal vein 1.0 to 1.2 cm.
  • Longitudinal length over 20 cm indicates hepatomegaly.

Doppler

  • Hepatic veins show a normal triphasic waveform, reflecting right atrial hemodynamics.
  • Portal flow hepatopetal (toward liver); hepatic vein flow hepatofugal (away).
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LIVER
Function & Technique

Function

  • Metabolism: converts glucose to and from glycogen, processes fats and proteins.
  • Digestion: secretes bile, excretes bilirubin. Storage: iron and vitamins. Detoxification: breaks down drugs, ammonia, and toxins.

Lab values & clinical

  • AST / ALT high suggests hepatocellular damage. Alk Phos / direct bilirubin high suggests obstruction.
  • Ordered for abnormal LFTs, RUQ pain, jaundice, suspected hepatomegaly.
  • Before scanning, correlate liver echotexture vs kidney, spleen, and pancreas, and vascular patency.

Scanning & protocol

  • NPO 6 to 8 hrs; 2.5 to 5 MHz curvilinear or sector probe; supine or RAO, deep inspiration.
  • Survey 4 planes: sagittal, transverse, coronal, subcostal oblique. Measure portal vein at end inspiration.
  • Adequacy: about 15 cm (up to 15 to 20); homogeneous; liver brighter than kidney, less bright than pancreas and spleen; vessels, ligaments, and fissures visible; smooth surface; balanced gain (TGC).
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Card 13  ·  Liver: Diffuse Disease  ·  Pathology
Front
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LIVER
Diffuse Disease
Illustration Fatty (bright) liver vs. normal parenchyma
Diffuse fatty change

Fatty liver (steatosis)

  • Fatty deposits within the hepatocytes; the most common diffuse liver disease. Common causes: alcohol, obesity, diabetes.
  • Diffusely echogenic (bright) liver; increased sound beam attenuation, so the deep liver and diaphragm penetrate poorly and hepatic vessel walls are hard to see.
  • Focal fatty sparing, often near the gallbladder or porta hepatis, is a normal island in a bright liver and can mimic a mass.

Acute hepatitis

  • Inflammation of the liver. The parenchyma may look normal, or the portal vein borders become brighter than usual, the "starry sky" sign, with hepatomegaly.
Trick: bright liver that hides the diaphragm points to fat
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LIVER
Cirrhosis & Portal HTN
Ultrasound Cirrhotic liver: nodular surface, coarse echotexture, ascites
Cirrhosis with surface nodularity

Cirrhosis

  • End stage chronic liver disease; regenerating nodules replace normal parenchyma. Progression: steatosis to steatohepatitis to cirrhosis to portal hypertension.
  • Sonographic: shrunken, echogenic right lobe; enlarged caudate and left lobes; nodular surface irregularity (best seen against ascites or with a high frequency linear probe); coarse echotexture.
  • Clinical: hepatomegaly early, then jaundice, ascites, and splenomegaly.

Portal hypertension

  • Portal vein enlarges; portosystemic collaterals develop and the umbilical (paraumbilical) vein can recanalize; splenomegaly and ascites follow.
  • Flow: normal hepatopetal portal flow slows, becomes biphasic, then reverses to hepatofugal (away from the liver) in severe disease.
Trick: "petal" toward  •  "fugitive" away, so reversed portal flow (hepatofugal) is the red flag
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Card 14  ·  Liver: Metabolic & Storage Disease
Front
SITM
LIVER
Deposition
UltrasoundMarkedly echogenic liver with poor penetration of the deep parenchyma
Increased parenchymal echogenicity

Glycogen storage disease

  • An inherited defect in glycogen metabolism causing accumulation within hepatocytes
  • Produces hepatomegaly with increased echogenicity, similar in appearance to fatty infiltration
  • Type I, von Gierke disease, carries an increased risk of hepatic adenoma
  • The adenoma is well demarcated, round, homogeneous, and echogenic, turning inhomogeneous when large

Hemochromatosis

  • Excess iron deposition in the liver, pancreas, and heart
  • The liver enlarges and echogenicity increases, although sonography cannot quantify iron
  • Carries an increased risk of hepatocellular carcinoma
  • Progresses to cirrhosis and portal hypertension, so the late picture converges on the cirrhotic liver

Wilson disease

  • Abnormal copper accumulation in the liver and brain
  • Progresses to cirrhosis, so the sonographic picture is usually that of the cirrhotic liver
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LIVER
Diffuse Disease Review
UltrasoundCoarse heterogeneous parenchyma with a nodular surface contour
Cirrhotic parenchymal pattern

Hepatocellular vs obstructive

  • Hepatocellular disease attacks the hepatocytes directly and interferes with liver enzymes
  • Obstructive disease blocks bile excretion
  • AST and ALT rise with hepatocellular damage; alkaline phosphatase and direct bilirubin rise with obstruction
  • ALT is more specific to the liver than AST, so ALT above AST points to a hepatic cause
  • A disproportional rise of alkaline phosphatase relative to bilirubin always suggests obstruction, and alk phos can rise before bilirubin

The diffuse family

  • Fatty infiltration, acute and chronic hepatitis, early alcoholic liver disease, and acute and chronic cirrhosis
  • Fatty infiltration is acquired and reversible, an intracellular accumulation of triglycerides, appearing diffuse or patchy

What sonography can and cannot say

  • It measures size, configuration, homogeneity, and contour
  • It cannot reliably distinguish the causes of a uniformly bright liver, so laboratory data and history carry the diagnosis
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Card 15  ·  Liver: Focal Lesions  ·  Pathology
Front
SITM
LIVER
Benign Lesions
Illustration Simple cyst and cavernous hemangioma
Common benign liver lesions

Simple hepatic cyst

  • Anechoic, round, smooth thin wall, with posterior acoustic enhancement (STAR criteria). Solitary or multiple.
  • Polycystic liver disease is associated with polycystic kidney disease.

Cavernous hemangioma

  • The most common benign tumor of the liver; a spongelike mass of blood filled spaces.
  • Typically well defined, homogeneous, and hyperechoic.

Other benign

  • Focal nodular hyperplasia and hepatic adenoma; adenoma is closely linked to oral contraceptive use.
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LIVER
Malignant & Infection
Ultrasound Hepatic metastases: multiple target lesions
Metastatic disease, target pattern

Hepatocellular carcinoma (HCC)

  • The most common primary liver malignancy; strongly linked to cirrhosis and chronic hepatitis.
  • Variable echogenicity; may invade the portal vein. Clinical: elevated AFP, weight loss.

Metastases

  • The liver is a common site for metastatic spread, and metastases are the most common malignant liver masses overall.
  • Multiple, variable echogenicity; may show a "target" or "bull's eye" pattern, an echogenic center with a hypoechoic halo.

Pyogenic abscess

  • A pus forming collection, often spread from appendicitis, diverticulitis, or cholecystitis.
  • Complex mass with internal echoes and debris; gas can cause dirty shadowing or ring down. Clinical: fever, hepatomegaly.
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Card 16  ·  Liver: Infectious & Inflammatory Lesions
Front
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LIVER
Abscess
Hepatic abscess on B mode and contrast enhanced ultrasound
Hepatic abscess, B mode and contrast enhanced

Pyogenic abscess

  • Usually a complex collection with irregular walls, internal debris, and posterior acoustic enhancement
  • May contain gas, which produces bright reflectors with dirty shadowing
  • Appearance ranges from nearly anechoic to almost solid depending on the internal consistency of the collection
  • Presents with fever, right upper quadrant pain, and leukocytosis
  • The right central lobe is the most common site, and 50 to 67 percent are multiple
  • Bacteria arrive by the biliary tree, the portal vein, the hepatic artery, direct extension, or trauma

Amebic abscess

  • Tends to be round or oval, hypoechoic, with low level internal echoes and a lack of significant wall echoes
  • Often abuts the liver capsule and may rupture through the diaphragm
  • Entamoeba histolytica invades the colonic mucosa and reaches the liver through the portal circulation

Where to look

  • Hepatic abscesses form in three sites, intrahepatic, subhepatic, and subphrenic, so search Morison pouch and the subdiaphragmatic space as well as the parenchyma
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LIVER
Parasitic & Fungal
UltrasoundCystic hepatic lesion containing detached undulating membranes
Echinococcal cyst with detached membrane

Echinococcal cyst

  • Hepatic echinococcosis is an infectious cystic disease seen in sheep herding regions
  • A cyst within a cyst, or daughter cysts inside a mother cyst, is the characteristic pattern
  • Detached, undulating membranes give the water lily sign
  • Wall calcification may occur

Hepatic candidiasis

  • Seen in immunocompromised patients
  • Multiple small lesions producing a wheel within a wheel or bulls eye pattern
  • Bull eye pattern in the early phase, becoming echogenic foci as lesions heal

Differential thinking

  • A complex cystic hepatic lesion with debris covers pyogenic abscess, echinococcal cyst, candidiasis, haemorrhagic cyst, and necrotic tumour. Clinical history separates them more reliably than the image
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Card 17  ·  Liver: Vascular Disorders
Front
SITM
LIVER
Budd-Chiari
UltrasoundHepatic veins that fail to fill with colour, with an enlarged caudate lobe
Hepatic venous outflow obstruction

Budd-Chiari syndrome

  • Obstruction of hepatic venous outflow, from thrombosis, tumour invasion, or a membranous web
  • In the acute phase the hepatic veins enlarge and thrombus may be visible
  • In chronic cases the veins become narrowed or are not identified at all, and intrahepatic collaterals develop
  • The caudate lobe hypertrophies because it drains directly into the IVC by its own small veins and is spared
  • Doppler shows absent, reversed, or continuous rather than triphasic hepatic vein flow
  • Primary Budd-Chiari is a congenital membranous web across the upper IVC at the hepatic vein entries. Secondary is thrombosis from oral contraceptives, pregnancy, tumour, infection, or a hypercoagulable state
  • The right lobe atrophies as the caudate hypertrophies, and that pairing is the classic morphology

Clinical

  • Presents with hepatomegaly, ascites, and abdominal pain
  • Associated with hypercoagulable states
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LIVER
Congestion
UltrasoundDistended hepatic veins and inferior vena cava that do not collapse with respiration
Passive hepatic congestion

Passive hepatic congestion

  • Develops secondary to congestive heart failure, with hepatomegaly
  • Laboratory data show normal to slightly elevated liver enzymes
  • The hepatic veins and IVC distend and lose their normal respiratory collapse
  • The hepatic vein waveform shows exaggerated atrial reversal
  • Long standing congestion can progress to cardiac cirrhosis
  • Congestion also dilates the superior mesenteric, portal, and splenic veins, not only the IVC and hepatic veins

Separating the two

  • Congestion distends the hepatic veins and they still connect to the IVC
  • Budd-Chiari obstructs them, so they narrow, thrombose, or disappear, and collaterals appear
Trick: Both give a big liver and ascites. The hepatic veins tell them apart: distended and patent is congestion, absent or reversed is Budd-Chiari.
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Gallbladder & Biliary

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Card 18  ·  Gallbladder & Biliary: Normal
Front
SITM
GALLBLADDER
Anatomy & Function
IllustrationLabeled biliary tree: liver, right and left hepatic ducts joining as common hepatic duct, cystic duct with spiral valves of Heister, gallbladder fundus/body/neck, common bile duct entering duodenum
Gallbladder and biliary tree, labeled.

Regions of the Gallbladder

  • Fundus: rounded distal tip, projects beyond the inferior liver edge.
  • Body: mid portion, contacts the duodenum, transverse colon, and anterior abdominal wall.
  • Neck: narrow proximal end, continuous with the cystic duct.

Biliary Tree

  • Cystic duct: lined by the spiral valves of Heister, arising in the neck.
  • Common hepatic duct + cystic duct: unite to form the common bile duct (CBD).
  • CBD: joins the pancreatic duct at the ampulla of Vater to enter the duodenum.

Size & Blood Supply

  • Roughly 7 to 10 cm long, up to about 4 cm wide; holds approximately 30 to 50 mL of bile.
  • Blood supply: cystic artery (branch of the right hepatic artery); venous return via the cystic vein.

Anatomic Variants

  • Phrygian cap: fundus folds back on itself.
  • Junctional fold: kink at the neck.
  • Hartmann pouch: small outpouching near the neck where stones commonly lodge.

Function

  • Stores and concentrates bile produced by the liver.
  • Contracts in response to a fatty meal, releasing bile to the duodenum for fat emulsification.
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GALLBLADDER
Sonographic Appearance & Protocol
UltrasoundLong-axis grayscale image of a normal gallbladder: anechoic pear-shaped lumen with a thin echogenic wall, main lobar fissure pointing from the GB neck toward the right portal vein
Long axis, normal gallbladder along the main lobar fissure.

Normal Sonographic Appearance

  • Lumen: anechoic, pear-shaped, with posterior enhancement.
  • Wall thickness: less than 3 mm, measured on the anterior wall.
  • CBD diameter: up to about 6 mm in adults under 60; add roughly 1 mm per decade after 60, and up to about 10 mm may be normal post-cholecystectomy.
  • Landmark: the main lobar fissure connects the neck of the gallbladder to the right portal vein.

Scanning Protocol

  • Patient prep: NPO for at least 6 hours so the gallbladder is fully distended.
  • Transducer: broadband curvilinear, 2.5 to 5 MHz.
  • Position: begin supine; roll to left lateral decubitus or upright to shift stones and separate small stones from the wall.
  • Image and measure the gallbladder in long and transverse; measure wall on the transverse view, anterior wall, outer margin to outer margin, with the beam perpendicular.
Trick: Follow the main lobar fissure like an arrow; it points straight from the right portal vein to the gallbladder neck.
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Card 19  ·  Gallbladder & Biliary: Ducts & Ductal Pathology
Front
SITM
GALLBLADDER
Biliary Anatomy
IllustrationRight and left hepatic ducts joining to form the common hepatic duct, then the common bile duct meeting the pancreatic duct
The biliary apparatus

The apparatus

  • Right and left hepatic ducts, common hepatic duct, common bile duct, the pear shaped gallbladder, and the cystic duct
  • Divided into intrahepatic and extrahepatic segments
  • Intrahepatic ducts run in the portal triads alongside the portal veins and hepatic arteries
  • The extrahepatic portion includes the common hepatic duct, the common bile duct, and part of the central right and left ducts

Course and junction

  • The right and left hepatic ducts emerge at the porta hepatis and unite into the common hepatic duct, which passes caudally and medially
  • The common bile duct is joined by the main pancreatic duct, and together they open through the ampulla of Vater into the duodenal wall

Relations

  • The common duct lies anterior and lateral to the portal vein; the hepatic artery lies anterior and medial to it
Trick: At the porta hepatis, duct to the right, artery to the left, portal vein behind both.

Normal caliber

  • The common bile duct measures up to 6 mm, borderline at 7 mm, dilated above 10 mm, and widens with age and after cholecystectomy
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GALLBLADDER
Ductal Pathology
UltrasoundDilated intrahepatic ducts running parallel to portal branches, the parallel channel sign
Intrahepatic biliary dilatation

Obstruction patterns

  • Dilated intrahepatic ducts run beside portal branches, giving the parallel channel or shotgun sign
  • Dilatation above the cystic duct with a normal gallbladder points to a proximal obstruction
  • A dilated duct plus a dilated gallbladder points to a lesion at or below the cystic duct
  • Intrahepatic ducts should stay under 40 percent of the adjacent portal vein, and peripheral ducts under 2 mm

Named lesions

  • Cholangiocarcinoma: tumour of the bile duct. A Klatskin tumour sits at the junction of the right and left hepatic ducts and causes intrahepatic dilatation with a collapsed gallbladder
  • Caroli disease: congenital saccular dilatation of the intrahepatic ducts
  • Choledochal cyst: cystic dilatation of the common bile duct, presenting in children with pain, jaundice, and a mass
  • Sclerosing cholangitis: irregular duct wall thickening with strictures, associated with inflammatory bowel disease
  • Cholangiocarcinoma is classified by site: intrahepatic, hilar (the Klatskin position), and distal. Most are hypoechoic and hypovascular

Compression from outside

  • Mirizzi syndrome: a stone impacted in the cystic duct or gallbladder neck compresses the common hepatic duct from outside, giving intrahepatic dilatation with a normal common duct
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Card 20  ·  Gallbladder: Stones & Obstruction
Front
SITM
GALLBLADDER
Cholelithiasis & Sludge
Gallbladder with layering sludge and dependent stones
Layering sludge with dependent gallstones

Word Roots

cholelithiasis
bilestonecondition

Bile stone condition. Swap lith for cyst and you get cholecystitis.

Cholelithiasis

  • Classic triad: echogenic, mobile, posterior acoustic shadowing within the gallbladder lumen.
  • Stones shift to the most dependent portion when the patient rolls into left lateral decubitus or upright.
  • WES sign (Wall, Echo, Shadow): a contracted, stone-filled gallbladder shown as a bright wall, a curved echogenic arc, and dense posterior shadow.

Biliary Sludge

  • Low-level, nonshadowing echoes that layer in the dependent gallbladder.
  • Moves slowly with changes in patient position.
  • Tumefactive sludge: fills the lumen and can appear isoechoic to liver, mimicking a mass; still nonshadowing and mobile.
Trick: Stones shadow and shift; sludge layers and lags; polyps stay put and cast no shadow.
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GALLBLADDER
Choledocholithiasis & Obstruction
UltrasoundPorta hepatis long axis showing a dilated common bile duct anterior to the portal vein (parallel channel sign) with an echogenic shadowing stone within the distal CBD; small inset of dilated intrahepatic ducts running parallel to portal branches
Dilated CBD with an impacted stone; dilated duct paralleling the portal vein at the porta hepatis.

Choledocholithiasis

  • Stone within the common bile duct, often lodged at the distal CBD.
  • Sonographic appearance mirrors gallstones: echogenic focus within the duct with posterior shadowing.
  • CBD greater than about 6 mm is considered dilated in adults under 60; add roughly 1 mm per decade after 60, and up to about 10 mm may be normal post-cholecystectomy.

Biliary Obstruction

  • Bile ducts expand outward from the point of obstruction; extrahepatic dilation occurs before intrahepatic dilation.
  • Dilated CBD paralleling the portal vein at the porta hepatis (often called parallel channel sign).
  • Dilated intrahepatic ducts coursing parallel to portal vein branches within the liver (too many tubes / shotgun sign).
  • Note: terminology varies across texts; some sources apply parallel channel and shotgun sign to the extrahepatic finding, so favor the anatomic description.
  • Courvoisier gallbladder: painless jaundice with a distended, non-inflamed gallbladder from distal CBD obstruction, classically a pancreatic head carcinoma.
Trick: One tube next to the portal vein is normal; two parallel tubes is the CBD talking back.
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Card 21  ·  Gallbladder: Wall & Inflammatory Pathology
Front
SITM
GALLBLADDER
Acute Cholecystitis
UltrasoundTransverse gallbladder with markedly thickened wall measured by calipers, gallstone impacted at the neck, and a rim of anechoic pericholecystic fluid tracking along the outer wall
Thickened gallbladder wall, impacted stone, and pericholecystic fluid.

Sonographic Findings

  • Wall thickening greater than 3 mm, measured on the anterior wall in transverse.
  • Distended lumen greater than 4 cm.
  • Gallstones, often with an impacted stone in Hartmann pouch or the cystic duct.
  • Pericholecystic fluid tracking along the gallbladder bed.

Sonographic Murphy Sign

  • Maximal tenderness reproduced when the transducer is pressed directly over the sonographically identified gallbladder.
  • Highly suggestive of acute cholecystitis when combined with wall thickening and stones.
  • May be diminished in advanced disease.
Trick: Think "3, 4, stone, sore": wall over 3 mm, lumen over 4 cm, stone impacted, positive Murphy under the probe.
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GALLBLADDER
Adenomyomatosis, Polyps & Porcelain GB
UltrasoundSplit image: focal fundal wall thickening with bright intramural foci throwing comet-tail artifact (adenomyomatosis) beside a non-mobile echogenic polyp attached to the anterior wall with no shadowing
Adenomyomatosis with comet-tail artifact and a wall-adherent polyp.

Adenomyomatosis

  • Benign hyperplasia of the gallbladder wall with Rokitansky-Aschoff sinuses.
  • Focal or diffuse wall thickening with small echogenic intramural foci.
  • Comet-tail artifact projecting from the wall into the lumen is characteristic.

Gallbladder Polyps

  • Echogenic soft tissue arising from the wall; most commonly cholesterol polyps.
  • Non-mobile with position change and produce no acoustic shadow.
  • May generate a comet-tail artifact, overlapping with adenomyomatosis.

Porcelain Gallbladder

  • Calcification of the gallbladder wall; typically clinically silent.
  • Wall appears as a bright echogenic curve with dense posterior shadowing, obscuring the lumen.
  • Associated with an increased risk of gallbladder carcinoma.
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Card 22  ·  Gallbladder: Other Cholecystitis
Front
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GALLBLADDER
Acalculous & Emphysematous
UltrasoundSplit panel: acalculous gallbladder with a thickened wall, layering sludge, and pericholecystic fluid but no stones in a critically ill patient; second panel showing bright echogenic foci within the gallbladder wall throwing dirty shadowing and ring-down artifact from intramural gas
Acalculous cholecystitis (left) and emphysematous cholecystitis with intramural gas (right).

Acalculous Cholecystitis

  • Cholecystitis without gallstones; seen in critically ill, trauma, burn, or post-op patients.
  • Sonographic findings mirror acute cholecystitis: wall thickening, sludge, pericholecystic fluid, positive sonographic Murphy, but no stones.
  • High morbidity; may progress rapidly to gangrene or perforation.

Emphysematous Cholecystitis

  • Gas within the gallbladder wall or lumen from gas-forming organisms; strongly associated with diabetes.
  • Bright echogenic foci with dirty shadowing and ring-down / reverberation artifact.
  • Gas rises to the non-dependent side and shifts with patient position, unlike stones.
Trick: No stones, sick patient, sick gallbladder equals acalculous; bright foci that rise instead of drop equals gas.
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GALLBLADDER
Gangrenous & Chronic
UltrasoundSplit panel: gangrenous gallbladder with a heterogeneous striated wall and intraluminal sloughed membranes; second panel showing a small contracted gallbladder wrapped around stones producing the wall-echo-shadow sign of chronic cholecystitis
Gangrenous cholecystitis with intraluminal membranes (left) and chronic cholecystitis with WES sign (right).

Gangrenous Cholecystitis

  • Advanced complication with wall necrosis; high risk of perforation.
  • Sonographic findings: heterogeneous or striated wall, intraluminal membranes from sloughed mucosa, focal wall defects.
  • Sonographic Murphy sign is often diminished or absent due to nerve damage.

Chronic Cholecystitis

  • Repeated inflammation from long-standing stones; wall becomes fibrotic and contracted.
  • Sonographic findings: small contracted gallbladder around stones, often producing the WES sign.
  • Wall thickening without acute inflammatory features (no pericholecystic fluid, negative Murphy).
Trick: Membranes and a quiet Murphy equals gangrene; small, stone-filled, silent equals chronic.
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Spleen

4 cards. Rate each from cut it to must keep, and note what to cut, add or reword. Highlight any words on a card to comment on them directly.

Card 23  ·  Spleen: Normal
Front
SITM
SPLEEN
Anatomy
IllustrationSpleen in LUQ, inferior to left hemidiaphragm, superolateral to left kidney, tail of pancreas at the splenic hilum
Spleen and neighbors, coronal view

Position & relations

  • Intraperitoneal organ of the left upper quadrant, just inferior to the diaphragm.
  • Left kidney lies inferior to the spleen.
  • Tail of the pancreas lies posterior to the stomach and lesser sac as it approaches the splenic hilum and splenic vessels.
  • A mass in the LUQ may displace the spleen inferiorly.

Function & parenchyma

  • Defense against disease (immune organ).
  • Hematopoiesis and erythropoiesis (active in the fetus).
  • Destruction and removal of flawed red blood cells and platelets.
  • Culling (destruction of aged or abnormal RBCs) and pitting (removal of intracellular inclusions from RBCs) occur in the red pulp.
  • Parenchyma is red pulp (venous sinuses, RBC turnover) plus white pulp (Malpighian corpuscles, the lymphoid follicles responsible for immune function).
  • Blood storage.

Variants: accessory spleen, polysplenia, asplenia

  • Accessory spleen (splenule): small round island of splenic tissue, typically located near the splenic hilum or near the tail of the pancreas.
  • Splenule appears isoechoic to the spleen on ultrasound.
  • Polysplenia: failure of fusion of splenic masses on the dorsal mesogastrium, producing multiple small spleens and often associated with cardiac or situs anomalies.
  • Asplenia: congenital absence of the spleen.
Trick: a splenule at the hilum can mimic a mass. Match its echotexture to the spleen to sort it out.
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SPLEEN
Sonographic & Technique
UltrasoundLongitudinal spleen with length measurement, upper margin near diaphragm to inferior margin
Longitudinal spleen with length measurement

Normal appearance

  • Homogeneous parenchyma; commonly isoechoic to slightly hyperechoic relative to the liver (references vary), and more echogenic than the left renal cortex.
  • Tubular structures visible at the splenic hilum.

Measurement

  • Measured on a longitudinal image from the upper margin (near the diaphragm) to the inferior margin.
  • Adult upper limit about 12 to 13 cm long axis; over 13 cm is splenomegaly; thickness over 6 cm also abnormal.
  • Compare parenchymal echogenicity to the liver on the same study.

Scanning technique

  • Coronal LUQ approach through intercostal spaces.
  • Right lateral decubitus opens the intercostal windows and brings the spleen into the coronal imaging plane; avoid steep decubitus, which can cause the spleen to fall away from the abdominal wall.
  • Deep inspiration brings the spleen into view.
  • Long axis of the spleen with color Doppler at the hilum; measure length. Transverse at the hilum; measure width.
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Card 24  ·  Spleen: Pathology
Front
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SPLEEN
Splenomegaly & Cyst
UltrasoundEnlarged spleen on longitudinal view with length caliper exceeding upper limit of normal
Splenomegaly, long axis

Mastery Check

  • Splenomegaly threshold
  • Congestive causes
  • Simple splenic cyst
  • Varices at the hilum

Fill in a circle when a topic feels solid.

Splenomegaly

  • Enlargement of the spleen beyond the upper limit of normal length on the longitudinal image.
  • Survey the parenchyma to confirm it remains uniform and homogeneous, aside from the tubular structures at the hilum.
  • When portal hypertension is suspected as the cause, closely evaluate the splenic hilum for abdominal varices.

Causes of congestive splenomegaly

  • Heart failure.
  • Portal hypertension, portal or splenic vein thrombosis.
  • Leukemia, lymphoma, mononucleosis.
  • Generalized infections, hemolytic anemias, glycogen storage disease.

Simple splenic cyst

  • Cystic masses are uncommon in the spleen; classified as congenital or acquired.
  • Sonographic findings: round, smooth walled, anechoic, with posterior enhancement.
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SPLEEN
Infarct & Trauma
UltrasoundPeripheral wedge shaped splenic infarct with base along the subcapsular surface
Splenic infarct, peripheral wedge

Splenic infarct

  • May show a localized hypoechoic area, depending on time of onset.
  • Fresh hemorrhage has a hypoechoic appearance.
  • Healed infarctions appear as echogenic, peripheral, wedge shaped lesions with their base toward the subcapsular surface.

Splenic trauma & rupture

  • After blunt injury a subcapsular hematoma may develop with subsequent rupture.
  • Assess for free fluid surrounding the splenic capsule in blunt abdominal trauma.
  • Small hypoechoic separation medial to the splenic capsule represents a subcapsular hematoma; inhomogeneity of the splenic texture may represent intraparenchymal hematoma.
  • Blood exhibits various echo patterns depending on the time since trauma.

Splenule vs mass

  • An accessory spleen is isoechoic to the spleen and typically sits at the hilum or near the pancreatic tail.
  • Match echotexture to the spleen to distinguish a splenule from a true splenic or peripancreatic mass.
Trick: splenosis (ectopic splenic implants) can follow splenic rupture and mimic peritoneal masses.
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Card 25  ·  Spleen: Masses
Front
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SPLEEN
Benign Masses
UltrasoundWell defined echogenic lesion within splenic parenchyma
Splenic hemangioma

Primary benign tumours

  • Primary tumours of the spleen are rare
  • The benign group is hemangioma, hamartoma, and lymphangioma
  • Hemangioma is the most common of them and usually appears as a well defined echogenic lesion
  • Hamartoma is hyperechoic with mixed solid and cystic components, well defined but not encapsulated

Cysts

  • Cystic masses are not common in the spleen
  • Classified as congenital (true, endothelial lined) or acquired (usually post traumatic, without a lining)
  • A simple splenic cyst shows the standard cystic criteria: thin wall, anechoic contents, and posterior enhancement
  • Echinococcus is the only parasite that forms splenic cysts. Look for daughter cysts, wall calcification, or fine internal echoes
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SPLEEN
Malignant & Infiltrative
UltrasoundMultiple hypoechoic lesions scattered through an enlarged spleen
Splenic lymphomatous involvement

Malignant tumours

  • Malignant splenic tumours are uncommon
  • Primary malignancies are lymphoma and hemangiosarcoma
  • Very rare primaries include malignant fibrous histiocytoma, leiomyosarcoma, and fibrosarcoma
  • Lymphoma is the most common malignant process to involve the spleen and often presents as splenomegaly with or without focal lesions
  • Splenic lymphoma takes four patterns: diffuse, focal small nodular, focal large nodular, and bulky. Lesions are typically hypoechoic

Storage and blood disorders

  • Storage diseases affecting the spleen: amyloidosis, Gaucher disease, Niemann-Pick disease
  • Erythropoietic abnormalities: sickle cell, hereditary spherocytosis, hemolytic anaemia, chronic anaemia, polycythemia vera, thalassaemia, and myeloproliferative disorders

Infection

  • The spleen may be infected in subacute bacterial endocarditis, septicaemia, immunocompromise, drug abuse, and after trauma or infarct
  • A pyogenic abscess is hypoechoic with septations and low level echoes. A gas containing abscess is echogenic with reverberation, and microabscesses give a bulls eye pattern

Metastases

  • The spleen is the tenth most common site of metastases, from breast, lung, ovary, stomach, colon, kidney, prostate, or melanoma. Lesions are usually well defined and range from hypoechoic to hyperechoic, including target and halo patterns
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Card 26  ·  Spleen: Trauma & Vascular
Front
SITM
SPLEEN
Trauma
UltrasoundCrescentic hypoechoic collection conforming to the splenic capsule
Subcapsular splenic hematoma

Red Flag Features

  • Free fluid in the LUQ
  • Irregular splenic contour
  • Crescentic subcapsular collection
  • Heterogeneous parenchyma
  • Falling haematocrit

Blunt trauma

  • The spleen is the organ most commonly injured in blunt abdominal trauma
  • Injuries include linear or stellate lacerations, capsular tears, puncture wounds from foreign bodies or rib fractures, and subcapsular hematomas
  • A subcapsular collection lies against the splenic capsule and shows a double contour sign, separating from splenic tissue

Appearance over time

  • An acute haematoma may appear hypoechoic and can still be hard to separate from splenic tissue, so it is easy to miss
  • It becomes progressively more lucent as it liquefies
  • Free fluid in Morison pouch or the left upper quadrant may be the only sign of injury

Delayed rupture

  • A contained subcapsular haematoma can rupture days after the injury, so a normal early scan does not close the question
Trick: Look for the fluid, not only the organ. A normal looking spleen with free fluid is still an abnormal study.
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SPLEEN
Vascular
UltrasoundPeripheral wedge shaped hypoechoic region with its base at the splenic capsule
Splenic infarct

Splenic infarct

  • Classically a peripheral wedge shaped lesion with its base at the capsule
  • Hypoechoic when acute, becoming more echogenic as it heals, and may leave a contour defect
  • Colour Doppler shows absent flow within the wedge
  • Seen with sickle cell disease, endocarditis, and embolic disease

Splenic artery

  • The splenic artery shows the greatest turbulence of the celiac branches, owing to its tortuosity
  • It is prone to aneurysm, so apply Doppler to any suspected mass at the hilum, since a splenic artery aneurysm can mimic a cystic or solid lesion

Splenic vein

  • Splenic vein thrombosis is classically a complication of pancreatitis, so look for it whenever pancreatitis is present
  • The splenic hilum contains both the splenic artery and vein, so use colour before calling any hilar lesion a node or mass
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Pancreas

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Card 27  ·  Pancreas: Normal
Front
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PANCREAS
Anatomy & Landmarks
IllustrationTransverse pancreas with head, uncinate, neck, body, and tail draped over SMA, SMV, splenic vein, aorta, and IVC
Pancreas and its retroperitoneal vascular landmarks

Word Roots

pancreas
allflesh

Greek: "all flesh", named for its uniform fleshy texture.

Four Regions

  • Head: largest portion, seated in the C-loop of the duodenum to the right of the SMV
  • Uncinate process: posteromedial extension of the head that hooks behind the SMV
  • Neck: short segment anterior to the SMV and portal confluence
  • Body and tail: extend leftward toward the splenic hilum

Vascular Landmarks

  • Posterior: aorta and IVC are the posterior landmarks of the gland
  • Splenic vein: hugs the posterior border of the body and tail; primary sonographic landmark
  • SMA and SMV: lie posterior to the neck and body; SMA sits to the left of the SMV
  • CBD: courses through the posterolateral head
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PANCREAS
Duct, Echotexture & Function
UltrasoundTransverse epigastric image with splenic vein posterior to body and thin anechoic pancreatic duct centrally
Normal pancreatic duct with splenic vein landmark

Pancreatic Duct (Duct of Wirsung)

  • Normal duct measures less than 2 mm
  • Seen centrally within the body as two parallel echogenic walls with an anechoic lumen

Echogenicity

  • Normally isoechoic to hyperechoic relative to the liver
  • The pancreas is typically more echogenic than the adjacent liver parenchyma
  • Gland atrophies and becomes more echogenic with advancing age from fatty replacement

Function

  • Exocrine: acini cells secrete digestive enzymes; amylase digests carbohydrates and lipase digests fats
  • Endocrine: islets of Langerhans secrete insulin and glucagon into the blood

Scanning Approach

  • Transverse epigastric plane is the primary window
  • Head with IVC and SMV; body and tail with SMV and SMA
  • Water in the stomach can be used as an acoustic window when bowel gas obscures the gland
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Card 28  ·  Pancreas: Ducts & Variants
Front
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PANCREAS
Ducts
IllustrationDuct of Wirsung running the length of the pancreas with the accessory duct of Santorini above it
Pancreatic ductal anatomy

Two ducts

  • The duct of Wirsung is the main pancreatic duct, running the length of the gland and joining the common bile duct at the ampulla of Vater
  • The duct of Santorini is the accessory duct, draining the upper head separately into the duodenum
  • A normal main duct measures up to about 2 mm and should taper smoothly toward the tail

Blood supply

  • Supplied by the splenic artery and the pancreaticoduodenal arteries
  • The splenic artery supplies body and tail through four branches: suprapancreatic, pancreatic, prepancreatic, and prehilar
  • The gastroduodenal artery runs along the anterolateral border of the head, just right of the neck, before dividing into the superior pancreaticoduodenal branches
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PANCREAS
Variants & Function
UltrasoundPancreatic head tissue encircling the second portion of the duodenum
Annular pancreas

Congenital variants

  • Annular pancreas: a rare anomaly in which the head surrounds the second portion of the duodenum, and can obstruct it
  • Pancreas divisum: failure of the dorsal and ventral ducts to fuse, so most drainage passes through the accessory duct
  • Ectopic pancreatic tissue may sit in the stomach or duodenal wall

Two glands in one

  • Exocrine: the acini cells produce up to 2 litres of pancreatic juice a day, which enters the duodenum with bile
  • Endocrine: the islets of Langerhans secrete glucagon and insulin into the blood
  • Delta cells are the third islet type and make somatostatin, which inhibits both insulin and glucagon

Enzymes

  • Both amylase and lipase rise in acute pancreatitis. Lipase is excreted specifically by the pancreas, rises earlier, and stays elevated longer
  • Glucose reflects the endocrine side
Trick: Lipase is the specific one. Amylase rises with salivary and bowel disease too.
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Card 29  ·  Pancreas: Inflammatory Pathology
Front
SITM
PANCREAS
Acute Pancreatitis
UltrasoundDiffusely enlarged hypoechoic pancreas with adjacent peripancreatic fluid
Diffuse acute pancreatitis with peripancreatic fluid

Sonographic Findings

  • Gland may appear normal early in the disease
  • Diffusely enlarged, hypoechoic pancreas from edema
  • Focal hypoechoic area within the gland in focal disease
  • Borders remain distinct but become irregular
  • Peripancreatic fluid collections; may progress to hemorrhage

Clinical & Labs

  • Elevated amylase within 24 hours
  • Elevated lipase within 72 hours; lipase is the more specific enzyme
  • Leukocytosis and elevated ALT may be present
  • Common causes include alcohol use, gallstones, and hypercalcemia
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PANCREAS
Pseudocyst & Chronic Pancreatitis
UltrasoundAnechoic pseudocyst arising from the pancreas with posterior enhancement
Pancreatic pseudocyst following acute pancreatitis

Pancreatic Pseudocyst

  • Complication of acute or chronic pancreatitis
  • Pancreatic juice escapes and collects in the anterior pararenal space
  • Typically anechoic with well-defined walls and posterior acoustic enhancement
  • May contain internal debris or septations after hemorrhage or infection
  • Extrapancreatic collections may resolve spontaneously within 4 weeks of onset

Pancreatic Abscess / Phlegmon

  • Complication of acute pancreatitis in which pancreatic enzymes accumulate in the surrounding space and become infected
  • Appears as a complex collection with internal debris, septations, and possible gas

Chronic Pancreatitis

  • Recurring destruction of pancreatic tissue leading to atrophy and fibrosis with scarring
  • Parenchymal calcifications within the gland cast posterior shadowing
  • Dilated pancreatic duct greater than 2 mm
  • Gland becomes small and heterogeneous
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Card 30  ·  Pancreas: Cystic & Endocrine Neoplasms
Front
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PANCREAS
Cystic Lesions
UltrasoundMultilocular cystic pancreatic mass with internal septations
Cystic pancreatic neoplasm

Benign cystic lesions

  • Autosomal dominant polycystic disease, von Hippel-Lindau syndrome, and cystic fibrosis all produce true pancreatic cysts

Four cystic neoplasms

  • The cystic neoplasms carry varying malignant potential: serous cystic tumours, mucinous cystic neoplasms, intraductal papillary mucinous neoplasms, and solid pseudopapillary neoplasms
  • Serous tumours tend to be microcystic with many small locules; mucinous tumours tend to be macrocystic with fewer, larger locules and higher malignant potential
  • IPMN communicates with the duct system, so a dilated main duct with no obstructing mass raises it
  • Solid pseudopapillary neoplasm: young women, usually the tail, heterogeneous solid and cystic, with lower malignant potential than the others
  • A central stellate scar, sometimes calcified, is classic for serous cystadenoma, the least likely of these to turn malignant

The one that is not a neoplasm

  • A pseudocyst is far more common than any of these and follows pancreatitis. The most common location is the lesser sac, anterior to the pancreas and posterior to the stomach
  • History decides: pancreatitis makes a pseudocyst likely, its absence makes a cystic neoplasm more likely
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PANCREAS
Endocrine Tumours
UltrasoundSmall well defined hypoechoic mass within the pancreatic tail
Islet cell tumour

Islet cell tumours

  • Arise from the islet cells and may be functional or nonfunctional, benign adenoma or malignant
  • The most common functioning islet cell tumour is insulinoma, followed by gastrinoma
  • Functional tumours present early because of their hormone effects, so they are usually small and hard to see
  • Typically well defined and hypoechoic to the surrounding parenchyma
  • Insulinoma presents with the Whipple triad: hypoglycaemic symptoms, a low measured blood sugar, and relief with intravenous glucose
  • Gastrinoma produces Zollinger-Ellison syndrome, gastric acid hypersecretion with recurrent peptic ulcers and diarrhoea. About 60 percent are malignant and many are multiple or extrapancreatic

Adenocarcinoma

  • The most common primary neoplasm of the pancreas
  • Most arise in the head, presenting with painless jaundice from common duct obstruction
  • Hypoechoic, ill defined mass that obstructs both the bile duct and the pancreatic duct, giving the double duct sign

Phlegmon

  • An inflammatory process spreading along fascial pathways, causing diffuse inflammatory oedema of soft tissue that may proceed to necrosis and suppuration
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Card 31  ·  Pancreas: Neoplastic Pathology
Front
SITM
PANCREAS
Adenocarcinoma
Hypoechoic mass in the pancreatic head
Adenocarcinoma of the pancreatic head

Mnemonic

The three P's of a head mass: Painless jaundice, Palpable gallbladder, Pancreatic head. Painless is the word that separates it from stones.

Sonographic Findings

  • Most common appearance is a hypoechoic mass in the head of the pancreas
  • Poorly defined focal mass with an irregular border
  • Focal enlargement and displacement of normal pancreatic parenchyma
  • Secondary enlargement of the common duct from edema or tumor invasion of the head

Associated Signs

  • Double duct sign: coexisting dilation of the common bile duct and the pancreatic duct
  • Courvoisier gallbladder: painlessly enlarged palpable gallbladder caused by a pancreatic head mass obstructing the CBD
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PANCREAS
Adenocarcinoma: Clinical & Search Pattern
IllustrationPancreatic head mass with simultaneously dilated CBD and pancreatic duct, plus a distended gallbladder
Double duct sign with Courvoisier gallbladder

Clinical Presentation

  • Painless jaundice is the classic presentation of a head mass obstructing the CBD
  • Weight loss and anorexia are common
  • Ampullary adenocarcinomas carry a better prognosis than pancreatic adenocarcinoma

Search Pattern

  • Identify the focal hypoechoic mass and document its region: head, body, or tail
  • When the mass is in the head, look for CBD and pancreatic duct dilation
  • Evaluate the gallbladder for painless distention (Courvoisier)
  • Survey the liver for metastatic disease and assess regional lymph nodes
Trick: A hypoechoic head mass with the double duct sign and a distended, non-tender gallbladder should raise concern for pancreatic adenocarcinoma.
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Gastrointestinal Tract

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Card 32  ·  Gastrointestinal Tract: Normal
Front
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GI TRACT
Anatomy
IllustrationStomach with fundus, body, and pylorus, the four duodenal segments, and the colon with its haustra
Regions of the gastrointestinal tract

Stomach and duodenum

  • Stomach in three parts: the fundus superiorly, the body forming the central axis, the pylorus distally
  • Duodenum in four segments: superior, descending, transverse, ascending

Small bowel and colon

  • Valvulae conniventes: large mucosal folds projecting into the small bowel lumen that slow the passage of food and increase absorption. Seen as linear echoes about 3 to 5 mm apart
  • Haustra: the sacculations that give the colon its segmented appearance
  • The vermiform appendix is a remnant of the apex of the cecum. It sits under McBurney point, the midpoint of a line from the right anterosuperior iliac spine to the umbilicus

Blood supply

  • The celiac, superior mesenteric, and inferior mesenteric arteries supply both small and large intestine
  • The celiac axis reaches the duodenum through its right gastric, gastroduodenal, and superior pancreaticoduodenal branches
  • Varices may arise from the gastroesophageal vessels
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GI TRACT
Wall & Technique
UltrasoundTransverse bowel loop showing the alternating echogenic and hypoechoic wall layers
The five layer bowel wall

Wall layers

  • The bowel wall has five layers. The odd numbered layers, first, third, and fifth, are echogenic; the even numbered layers, second and fourth, are hypoechoic
  • Average total thickness is about 3 mm when distended and 5 mm when undistended

Landmarks

  • The gastroesophageal junction is seen on the sagittal scan just left of midline as a target or bull eye, anterior to the aorta, posterior to the left lobe of the liver, and inferior to the hemidiaphragm
  • The duodenum outlines readily with water ingestion or a change in patient position

Technique and limits

  • Intraluminal air produces an echogenic shadow that stops the beam, which is why much of the tract is difficult to assess
  • The small bowel is usually not resolved beyond the valvulae conniventes
  • Digestion and absorption are the primary functions of the tract
  • Peristalsis is the discriminator: bowel changes shape under gentle transducer pressure while lymph nodes hold theirs
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Card 33  ·  Gastrointestinal Tract: Upper Tract Pathology
Front
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GI TRACT
Stomach
UltrasoundGastric wall thickening with a hypoechoic rim surrounding an echogenic lumen
Target appearance of gastric wall thickening

Gastric masses

  • Leiomyoma is the most common tumor of the stomach
  • Gastric carcinoma is the fifth leading cause of cancer and the third leading cause of cancer death
  • A polyp is a protruding, space occupying epithelial lesion within the stomach

Other gastric findings

  • Gastric bezoar: an intragastric mass made of accumulated ingested material
  • Duplication cyst criteria, all three required: lined with alimentary tract epithelium, a well developed muscular wall, and continuity with the stomach
Trick: A thickened hypoechoic wall around an echogenic lumen is the target or pseudokidney appearance. It flags bowel wall pathology without naming the cause.
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GI TRACT
Small Bowel
UltrasoundDilated fluid filled small bowel loops proximal to a point of obstruction
Dilated loops in small bowel obstruction

Obstruction

  • Small bowel obstruction shows dilation of the loops proximal to the site of obstruction
  • Fluid filled loops transmit sound, so an obstructed bowel is often easier to image than a normal one
  • Paralytic ileus dilates bowel without a mechanical obstructing point

Other lesions

  • Meckel diverticulum: a pouchlike herniation through the muscular wall of a tubular organ
  • Lymphomatous involvement of the intestinal wall can produce a pseudokidney or hydronephrotic pseudokidney appearance
  • Diverticulum: an outpouching of the wall, most often colonic
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Card 34  ·  Gastrointestinal Tract: Appendix & Lower Tract
Front
SITM
GI TRACT
Appendicitis
UltrasoundNoncompressible blind ending tubular structure in the right lower quadrant with a thickened wall
Inflamed appendix on graded compression

Red Flag Features

  • Wall over 2 mm thick
  • Will not compress
  • Appendicolith with shadow
  • Asymmetric wall thickening
  • Surrounding free fluid

Acute appendicitis

  • Results from luminal obstruction and inflammation, leading to ischemia of the vermiform appendix
  • Presents with pain and rebound tenderness, usually localized over the right lower quadrant
  • Wall edema measures greater than 2 mm thick
  • Asymmetric wall thickening raises the possibility of perforation

Scanning it

  • High frequency linear transducer with graded compression over the point of maximum tenderness
  • A normal appendix compresses. An inflamed appendix does not
  • An appendicolith appears as an echogenic focus with posterior shadowing
  • Follow the blind ending tube to its tip; a normal tip does not exclude disease if the base was not seen
Trick: Compressibility is the whole test. If it flattens under the transducer, it is not an inflamed appendix.
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GI TRACT
Lower Tract
UltrasoundThickened terminal ileal wall with loss of the normal layered pattern
Bowel wall thickening in inflammatory disease

Inflammatory disease

  • Crohn disease is regional enteritis, a recurrent granulomatous inflammatory disease affecting the terminal ileum, the colon, or both, at any level
  • Inflamed segments show wall thickening with loss of the normal five layer pattern

Appendiceal and peritoneal

  • Mucocele of the appendix: gross enlargement of the appendix from accumulation of mucoid substance within the lumen
  • Pseudomyxoma peritonei: mucinous material distributed through the peritoneal cavity
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Peritoneal Cavity & Abdominal Wall

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Card 35  ·  Peritoneal Cavity & Abdominal Wall: Anatomy
Front
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PERITONEUM
Anatomy
IllustrationSagittal section showing the greater sac, the lesser sac behind the stomach, and the subphrenic and subhepatic spaces
Peritoneal spaces in sagittal section

Two layers, two sacs

  • The parietal peritoneum lines the walls of the cavity; the visceral peritoneum covers the abdominal organs
  • The general peritoneal cavity is the greater sac
  • The lesser sac, or omental bursa, is the peritoneal recess posterior to the stomach
  • The cavity contains the greater and lesser omentum, the mesenteries, the ligaments, and the fluid spaces

Why the attachments matter

  • The peritoneal attachments to the walls and organs determine where abnormal fluid can collect and how it moves
  • Because of the coronary ligament attachments, a collection in the right posterior subphrenic space cannot extend between the bare area of the liver and the diaphragm
  • The bare area is delineated by the right superior and inferior coronary ligaments, which separate the posterior subphrenic space from the right superior subhepatic space, Morison pouch
  • Ligaments on the right of the liver form the subphrenic and subhepatic spaces
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PERITONEUM
Fluid & Collections
UltrasoundAnechoic free fluid outlining bowel loops in the dependent portion of the abdomen
Free fluid in the peritoneal cavity

Pelvic compartments

  • The retrovesical space is divided by the uterus into an anterior vesicouterine recess and a posterior rectouterine sac, the pouch of Douglas
  • The pouch of Douglas is the most dependent part of the peritoneal cavity in the supine patient, so free fluid gathers there

Ascites

  • Ascites is the accumulation of serous fluid in the peritoneal cavity
  • Simple ascites is anechoic and shifts with position; inflammatory or malignant ascites tends to carry internal echoes, septations, or matted bowel
  • The hepatorenal recess, Morison pouch, is a dependent space where small volumes collect first

Abscess

  • An abscess is a cavity formed by necrosis within solid tissue, or a circumscribed collection of purulent material
  • A gas containing abscess shows bright reflectors with dirty shadowing and reverberation
  • Named collections to look for: lesser sac, subphrenic, subcapsular, biloma
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Card 36  ·  Peritoneal Cavity & Abdominal Wall: Pathology
Front
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PERITONEUM
Mesentery & Omentum
UltrasoundHypoechoic band following the convexity of the anterior abdominal wall
Omental band in lymphoma

How masses behave

  • A mass in the mesentery or omentum may be cystic or solid; a mass within the peritoneum tends to show an infiltrative pattern
  • With an omental mass, at least one third are malignant, and secondary neoplasms outnumber primary
  • In the mesentery, a benign primary tumor is more common than a malignant one, secondary neoplasms still outnumber primary, and a cystic mass is more common than a solid one

Named lesions

  • Lymphoma presents as a uniformly thick, hypoechoic, band shaped structure following the convexity of the anterior and lateral abdominal wall, the omental band
  • Secondary tumors and lymphoma are the neoplasms that most commonly involve the peritoneum and mesentery
  • Urachal cyst: incomplete regression of the urachus during development
  • Urinoma: an encapsulated collection of urine from closed renal injury, surgery, or an obstructing lesion
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PERITONEUM
Abdominal Wall
UltrasoundHypoechoic collection within the rectus muscle sheath
Rectus sheath hematoma

Wall lesions

  • Lesions of the superficial abdominal wall include inflammatory lesions, hematomas, neoplasms, hernias, and postsurgical lesions
  • Rectus sheath hematoma: an acute or chronic collection of blood lying within the rectus muscle or between the muscle and its sheath
  • Lymphocele: a fluid collection appearing after surgery in the pelvis, retroperitoneum, or recess cavities
  • Neoplasms of the wall include lipomas, desmoid tumors, and metastases

Hernia

  • An abdominal hernia is the protrusion of a peritoneal lined sac through a defect in the weakened abdominal wall
  • Scan the defect at rest and during Valsalva, since a reducible hernia may only appear on strain
Trick: A hernia is a moving diagnosis. If the patient does not strain, a reducible sac stays hidden and the study reads normal.
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Urinary System

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Card 37  ·  Urinary System: Normal
Front
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KIDNEY
Anatomy
IllustrationCoronal kidney showing cortex, medullary pyramids, columns of Bertin, renal sinus, capsule, and hilum
Renal anatomy

Location & Coverings

  • Retroperitoneal, paired organs
  • Three coverings from inner to outer: fibrous true capsule, perinephric (perirenal) fat, and Gerota's fascia
  • Hilum transmits renal artery, renal vein, and ureter

Parenchyma & Sinus

  • Parenchyma = renal cortex plus renal medulla
  • Medullary (renal) pyramids are triangular structures within the medulla
  • Columns of Bertin are cortical tissue extending between pyramids
  • Central renal sinus contains fat, calyces, pelvis, and vessels

Vasculature

  • Renal artery divides into about 5 segmental branches
  • Renal vein drains into the IVC

Function

  • Filter blood, produce urine, and maintain homeostasis
  • Urine drains calyces to renal pelvis to ureter to bladder
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KIDNEY
Sonographic Appearance
UltrasoundLong right kidney using liver as acoustic window with hypoechoic pyramids and echogenic central sinus
Normal long right kidney

Size

  • Normal adult kidney typically greater than 8 cm in longitudinal length
  • Average length 10 to 12 cm
  • Measure bipolar (pole to pole) long axis length

Echogenicity

  • Normal cortex is hypoechoic to or isoechoic with adjacent liver or spleen
  • Cortex should measure more than 1 cm in thickness
  • Medullary pyramids appear as triangular hypoechoic areas
  • Renal sinus is the brightest region (echogenic fat)

Scanning

  • Right kidney: use liver as an acoustic window
  • Left kidney: use spleen as an acoustic window
  • Slight decubitus rolls the liver anterior to the right kidney for better access
  • Document renal echogenicity compared with liver and spleen

Bladder

  • Anechoic when distended with homogeneously echogenic wall
  • Wall uniform in thickness, less than 3 mm when well distended
  • Color Doppler shows ureteral jets entering from the trigone at the posterolateral bladder base

Renal Function Labs

  • BUN and creatinine are the standard renal function labs
  • Both are elevated in renal failure
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Card 38  ·  Urinary System: Congenital Variants & Pseudotumors
Front
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KIDNEY
Pseudotumors
UltrasoundBand of cortical tissue extending inward between two pyramids
Prominent column of Bertin

Normal variants that mimic mass

  • Column of Bertin: a prominent invagination of cortex located at varying depths within the medullary substance. It is cortex, so it is isoechoic to cortex and continuous with it
  • Dromedary hump: a bulge of cortical tissue on the lateral surface, usually of the left kidney
  • Junctional parenchymal defect: a triangular echogenic area, typically anterior and superior
  • Sinus lipomatosis: deposition of fat in the renal sinus with parenchymal atrophy

Telling variant from tumour

  • A variant is isoechoic to normal cortex, continuous with it, and does not distort the outer contour
  • A true mass distorts the contour, differs in echogenicity, and displaces rather than continues the parenchyma
  • A hypertrophied column does not exceed 3 cm, indents the sinus laterally, and stays continuous with the cortex
Trick: A pseudotumour is made of the same tissue it sits in. If it matches cortex exactly, it probably is cortex.
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KIDNEY
Congenital Anomalies
IllustrationKidneys fused at their lower poles across the midline anterior to the spine
Horseshoe kidney

Fusion and position

  • Horseshoe kidney is the most common anomaly of renal fusion. Fusion of the lower poles occurs in 96 percent of cases, the ureters pass anterior to the parenchyma, and the blood supply varies
  • Renal ectopia: a kidney not in its usual position within the renal fascia
  • Renal hypoplasia: incomplete development, usually with fewer than five calyces
  • The isthmus lies anterior to the spine and can be mistaken for a solid pelvic mass or enlarged nodes

Duplication

  • Incomplete or partial duplication is the most frequently occurring congenital anomaly in the neonate: two collecting systems and two ureters, with a single ureter entering the bladder
  • Complete duplication is rarer, with two separate systems each having its own ureter reaching the bladder
  • The Weigert-Meyer rule: in a double ureter, the ureter draining the upper pole opens below and medial to the one from the lower pole
  • At the mid pole in transverse the duplex sinus is faceless, two echogenic sinus regions split by parenchyma with no single central pelvis. Two ureteral jets on one side confirm complete duplication
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Card 39  ·  Urinary System: Vasculature & Doppler
Front
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KIDNEY
Renal Vessels
IllustrationRenal artery branching into segmental, interlobar, arcuate, and interlobular vessels
Renal arterial tree

Arterial anatomy

  • The renal arteries are lateral branches of the aorta arising just inferior to the superior mesenteric artery
  • The artery divides into segmental, then interlobar arteries running between pyramids, then arcuate arteries arching over the bases of the pyramids, then interlobular arteries into the cortex
  • At least 30 percent of people have accessory renal arteries

Venous anatomy

  • Five to six veins join to form each main renal vein, emerging from the hilum anterior to the renal artery
  • The left renal vein crosses anterior to the aorta and posterior to the superior mesenteric artery

The nephron

  • The renal corpuscle is a capillary network, the glomerulus, surrounded by Bowman capsule
  • Blood enters through an afferent arteriole and leaves through an efferent arteriole
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KIDNEY
Doppler
UltrasoundLow resistance renal arterial waveform with continuous diastolic flow
Normal renal artery waveform

Normal waveform

  • The main renal artery is nonresistive, with significant diastolic flow, usually 30 to 50 percent of peak systole
  • Continuous diastolic flow provides continuous perfusion of the kidney
  • Spectral broadening occurs in both systole and diastole
  • Segmental, interlobar, and arcuate arteries show a similar pattern with progressively dampened, lower velocity flow toward the periphery
  • The normal intrarenal waveform has a rapid systolic upstroke and an early systolic peak

Resistive index

  • Calculated from peak systolic and end diastolic velocity
  • Normal peak systolic velocity is under 160 cm per second and the normal resistive index is 0.70 or less
  • A raised RI is nonspecific and points to medical renal disease, obstruction, or transplant dysfunction rather than any single cause

Practical limits

  • Renal artery stenosis is hard to exclude in a native kidney because the origin and full course are difficult to see
  • Occlusion can only be declared when the artery is unquestionably imaged, and collaterals can be mistaken for a patent vessel
  • Stenosis criteria: PSV above 180 cm per second at the narrowing, a downstream tardus and parvus waveform with acceleration time under 0.1 second, and a smaller kidney
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Card 40  ·  Urinary System: Bladder & Ureter
Front
SITM
KIDNEY
Ureter
IllustrationUreter descending from the renal pelvis with its three points of narrowing marked
The three ureteral constrictions

Ureteral anatomy

  • The renal pelvis divides into two or three major calyces, each dividing into two or three minor calyces
  • Three constrictions occur along the ureter: where it leaves the renal pelvis, where it crosses the pelvic brim, and where it pierces the bladder wall
  • Those three points are where calculi lodge, which is why they are worth knowing by position

Ureteral jets

  • Colour Doppler shows urine entering the bladder from each ureteral orifice
  • Present and symmetric jets argue against complete obstruction on that side
  • Absence of a jet is suggestive but not diagnostic, since jets are intermittent
  • Jets run upward and toward the opposite side, entering from the posterolateral bladder floor

Ureterocele

  • Cystic dilatation of the distal ureter within the bladder, seen as a thin walled cyst at the trigone
  • Associated with the upper pole moiety of a duplicated system
  • Shows a cobra head appearance on sagittal view of the bladder base
  • An ectopic ureterocele is commoner in females and usually arises from the upper pole ureter of a complete duplication, inserting low near the bladder neck
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KIDNEY
Bladder Pathology
UltrasoundIrregular soft tissue projection arising from the bladder wall into the lumen
Bladder wall mass

Bladder masses

  • Transitional cell carcinoma accounts for 90 percent of malignancies involving the renal pelvis, ureter, and bladder
  • It appears as an irregular, immobile projection from the wall, and colour flow within it separates a tumour from adherent clot
  • Blood clot moves with position change; tumour does not

Wall changes

  • Diffuse wall thickening follows chronic outlet obstruction, producing trabeculation and diverticula
  • A diverticulum is an outpouching connected by a neck, best shown by scanning through the connection
  • Measure wall thickness only on a reasonably distended bladder, since an empty bladder always looks thick
  • A diverticulum has no muscular layer, so stasis, recurrent infection, and stones are common inside it

Postvoid residual

  • Measured in three dimensions and multiplied by 0.52 for an ellipsoid volume
  • A significant residual supports outlet obstruction and explains upstream dilatation
  • A residual under 20 mL is normal in an adult

Cystitis

  • The wall may be normal at first, then hypoechoic and thickened as inflammation continues, and finally echogenic and fibrotic in chronic disease
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Card 41  ·  Urinary System: Cystic & Obstructive
Front
SITM
KIDNEY
Hydronephrosis
UltrasoundLong kidney with anechoic dilated central collecting system separating the calyces
Dilated collecting system

Definition

  • Dilation of the renal collecting system
  • Formal systems include SFU Grades I to IV and RAD I to V; also described descriptively as mild, moderate, severe

Sonographic Findings

  • Anechoic distension of the renal pelvis and calyces
  • Mild: distension of the renal pelvis
  • Moderate: pelvis and calyces dilate further with ballooning
  • Severe: marked dilation with cortical thinning

Simple Renal Cyst (Bosniak I)

  • Round or oval, anechoic with no internal echoes
  • Thin, well-defined walls with sharp interface to parenchyma
  • Posterior acoustic enhancement (through transmission)
  • No color flow within the mass
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KIDNEY
ADPKD
UltrasoundEnlarged kidney with numerous bilateral cortical cysts replacing much of the parenchyma
ADPKD

Autosomal Dominant Polycystic Kidney Disease

  • Previously known as adult polycystic kidney disease
  • Presents with hypertension, flank pain, and progressive renal failure

Sonographic Findings

  • Bilateral enlarged kidneys containing numerous cortical renal cysts
  • Cysts vary in size and may distort the normal renal contour
  • Associated hepatic cysts may be present

Distinguishing from Simple Cysts

  • Multiple bilateral cysts with kidney enlargement, not a solitary lesion
  • Progressive replacement of normal parenchyma
  • Screen the liver for associated cysts
Trick: Bilateral, numerous, and enlarged kidneys with liver cysts points to ADPKD rather than incidental simple cysts.
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Card 42  ·  Urinary System: Masses & Stones
Front
SITM
KIDNEY
Urolithiasis
UltrasoundEchogenic focus within the renal sinus casting a clean posterior acoustic shadow
Renal calculus with shadowing

Clinical

  • Renal colic, hematuria, oliguria, urinary tract infection

Sonographic Findings

  • Echogenic focus that produces posterior acoustic shadowing
  • Twinkle sign seen posterior to the calculus on color Doppler
  • May cause upstream hydronephrosis if obstructing

Pitfall

  • Prominent renal sinus fat, mesenteric fat, and bowel gas can appear as an indistinct echogenic focus with questionable shadowing
  • Twinkle artifact helps confirm a true stone
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KIDNEY
Solid Renal Masses
Solid cortical renal mass with calipers
Solid renal mass

Renal Cell Carcinoma

  • Solid mass on the kidney, hypoechoic, isoechoic, or hyperechoic
  • Can have a complex cystic appearance
  • Consider RCC, oncocytoma, angiomyolipoma, transitional cell carcinoma, and secondary neoplasms when a solid mass is detected

Angiomyolipoma

  • Benign fat-containing tumor of the kidney
  • Classically well defined and markedly hyperechoic (fat)
  • A small hyperechoic RCC can mimic it

Mimic to Exclude

  • Hypertrophied column of Bertin is a normal variant that can mimic a mass
  • Confirm continuity with adjacent cortex and matching echogenicity
Trick: A well-defined hyperechoic renal mass suggests angiomyolipoma, but RCC can also appear hyperechoic, so correlate and follow up.
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Card 43  ·  Urinary System: Infection
Front
SITM
KIDNEY
Pyelonephritis
Acute pyelonephritis
Acute pyelonephritis

Acute pyelonephritis

  • Bacterial infection of the renal parenchyma, usually ascending from the lower tract
  • The kidney is often normal on ultrasound, which is the single most important point
  • When abnormal: enlargement, loss of corticomedullary differentiation, and focal hypoechoic or hyperechoic areas of oedema
  • Presents with fever, flank pain, and leukocytosis
  • Renal infection is a spectrum: pyelonephritis, then focal bacterial nephritis, then abscess. A perinephric abscess arises by direct extension

Complications

  • Renal abscess, pyonephrosis, xanthogranulomatous pyelonephritis, emphysematous pyelonephritis, and chronic pyelonephritis
  • Focal bacterial nephritis shows a slightly hyperechoic, avascular focal area on colour Doppler

Pyonephrosis

  • Pus within an obstructed collecting system
  • Dilated collecting system containing low level echoes or a debris fluid level
  • A surgical emergency, and the reason debris in a dilated system is never dismissed
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KIDNEY
Severe Infection
UltrasoundBright echogenic foci within the renal parenchyma casting dirty shadows
Gas within the kidney

Emphysematous pyelonephritis

  • Gas forming infection of the parenchyma
  • Occurs almost exclusively in diabetic and immunocompromised patients
  • Fever, flank pain, and leukocytosis
  • Bright echogenic foci with dirty shadowing and reverberation, which can obscure the kidney entirely
  • E. coli is the usual organism, and severe cases can need emergency nephrectomy

Xanthogranulomatous pyelonephritis

  • Chronic infection associated with obstruction and a staghorn calculus
  • The kidney enlarges and loses function, with dilated calyces replaced by inflammatory tissue
  • The kidney is enlarged, with dilated calyces replaced by cystic inflammatory spaces around the stone
  • Peripelvic fibrosis can stop the staghorn calculus from shadowing

Chronic pyelonephritis

  • Repeated infection produces a small, scarred kidney with an irregular echogenic cortex and loss of corticomedullary differentiation
Trick: A bright kidney full of gas in a diabetic patient is emphysematous until proven otherwise. Do not read the shadowing as bowel.
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Card 44  ·  Urinary System: Medical Renal Disease
Front
SITM
KIDNEY
Parenchymal Disease
UltrasoundKidney with cortex brighter than adjacent liver and preserved pyramids
Increased cortical echogenicity

The sonographic pattern

  • Medical renal disease is the general term for parenchymal disease affecting the nephrons rather than a mass or obstruction
  • The hallmark is increased cortical echogenicity, judged against the adjacent liver or spleen
  • Normal cortex is less echogenic than liver. Cortex equal to or brighter than liver is abnormal
  • The pyramids stand out against the bright cortex early in disease, then differentiation is lost as it progresses
  • The strict criterion is cortex equal to or brighter than the adjacent liver or spleen, and cortex equal to the renal sinus in the same image

Grading by comparison

  • Compare cortex to liver on the right and cortex to spleen on the left in the same image, so gain settings apply to both

The limitation

  • The pattern is nonspecific. It says the nephrons are diseased, not which disease it is

Two patterns

  • Type I brightens the cortex but preserves or exaggerates the corticomedullary junction. Type II distorts anatomy and obliterates that junction, focally or diffusely
  • Some acute conditions do the opposite, enlarging the kidneys with decreased echogenicity from interstitial edema, as in acute renal vein thrombosis, acute pyelonephritis, and acute rejection
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KIDNEY
Chronic Renal Failure
UltrasoundSmall echogenic kidney with a thin cortical rim
End stage renal disease

Causes of the bright kidney

  • Glomerulonephritis, acute tubular necrosis, diabetic nephropathy, HIV nephropathy, and interstitial nephritis
  • HIV nephropathy classically gives markedly echogenic kidneys that stay normal in size or enlarge
  • Acute tubular necrosis is the most common medical cause of acute renal failure, giving bilaterally enlarged kidneys with hyperechoic pyramids
  • Nephrocalcinosis: the medullary form makes the pyramids brighter than the cortex, usually from hyperparathyroidism or renal tubular acidosis. The cortical form spares them

Chronic renal failure

  • The kidneys become small with a thin, echogenic cortex and loss of corticomedullary differentiation
  • Size is the discriminator: a bright large kidney suggests acute or infiltrative disease, a bright small kidney suggests chronic end stage disease
  • Acquired cystic disease develops in long term dialysis patients and carries an increased risk of renal cell carcinoma

Laboratory correlation

  • BUN is the concentration of urea nitrogen in blood, the end product of cellular metabolism
  • Hematuria is blood cells in the urine and can accompany early renal disease
  • Leukocytes appear with inflammation, infection, or tissue necrosis anywhere in the urinary tract
  • Serum creatinine is more specific and more sensitive than BUN for renal impairment
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Card 45  ·  Urinary System: Transplant & Trauma
Front
SITM
KIDNEY
Renal Transplant
UltrasoundTransplanted kidney in the iliac fossa scanned through the anterior abdominal wall
Renal allograft in the iliac fossa

The transplant

  • Placed extraperitoneally in the iliac fossa, so it is superficial and imaged with a higher frequency transducer than a native kidney
  • Baseline size, cortical echogenicity, collecting system, and resistive index are recorded so later studies have something to compare against

Fluid collections by timing

  • Hematoma: immediately postoperative
  • Urinoma: early, within days to weeks, from a leak at the ureteric anastomosis
  • Lymphocele: weeks to months later, typically medial to the graft, often septated
  • Abscess: any time, with debris, gas, and clinical sepsis

Dysfunction

  • A rising resistive index with graft enlargement and loss of corticomedullary differentiation suggests rejection, but the finding is nonspecific and biopsy decides
  • Acute rejection can present as an enlarged graft with decreased parenchymal echogenicity from interstitial edema
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KIDNEY
Trauma
UltrasoundPerinephric fluid collection with an irregular parenchymal defect
Renal injury with perinephric collection

Renal trauma

  • Ranges from contusion, through laceration, to a shattered kidney and pedicle injury
  • Subcapsular haematoma conforms to the capsule and flattens the parenchyma; perinephric haematoma spreads into the perirenal space
  • Appearance varies with age. An acute haematoma is usually echogenic and may look complex, becoming more anechoic as the clot lyses
  • Colour Doppler assesses perfusion, since a devascularized kidney can look structurally intact

Metastases

  • Metastases to the kidneys are relatively common and occur late in the disease course
  • Bilateral in about one third of cases and multiple in more than half
  • The common primaries are carcinoma of the lung or breast, and renal cell carcinoma of the contralateral kidney
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Retroperitoneum

3 cards. Rate each from cut it to must keep, and note what to cut, add or reword. Highlight any words on a card to comment on them directly.

Card 46  ·  Retroperitoneum: Spaces & Adrenal Anatomy
Front
SITM
RETROPERITONEUM
Spaces
IllustrationAxial section showing the anterior pararenal, perirenal, and posterior pararenal spaces around the kidney
The three retroperitoneal compartments

Boundaries

  • The retroperitoneal space lies between the posterior parietal peritoneum and the posterior abdominal wall muscles, extending from the diaphragm to the pelvis
  • Laterally it reaches the extraperitoneal fat planes within the transversalis fascia; medially it encloses the great vessels

Three compartments

  • Perirenal space: the kidney, the adrenal, and perirenal fat
  • Anterior pararenal space: the duodenum, the pancreas, and the ascending and transverse colon
  • Posterior pararenal space: the iliopsoas muscle, the ureter, and branches of the IVC and aorta with their lymphatics

Node bearing areas

  • Two major lymph node bearing areas: the iliac and hypogastric nodes within the pelvis, and the para-aortic group in the upper retroperitoneum
  • The prevesical space runs from the pubis to the anterior margin of the bladder; the presacral space lies between the rectum and the fascia over the sacrum
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RETROPERITONEUM
Adrenal Anatomy
UltrasoundLongitudinal right upper quadrant view through the liver showing the adrenal region above the upper pole of the right kidney
Right adrenal region through the liver

Position and shape

  • The right adrenal sits more superior to the kidney; the left sits more medial to it
  • The right adrenal has a comma or triangular shape in the transaxial plane
  • A single vein drains each gland: the right into the IVC, the left into the left renal vein

How to find them

  • Right: scan longitudinally through the right lobe of the liver, perpendicular to the linear right crus of the diaphragm
  • Left: harder because of stomach gas. Place the patient right lateral decubitus, scan along the posterior axillary line using the spleen and left kidney as a window, in deep inspiration
  • Recognize retroperitoneal fat as separate from the liver, the crus, the gland, and the great vessel

Pitfalls that mimic the gland

  • Right crus of the diaphragm, the second portion of the duodenum, the gastroesophageal junction, medial lobulations of the spleen, splenic vasculature, the body and tail of the pancreas, and the fourth portion of the duodenum
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Card 47  ·  Retroperitoneum: Adrenal Pathology
Front
SITM
RETROPERITONEUM
Cortical Syndromes
IllustrationAdrenal gland in cross section with the outer cortex and the inner medulla labeled
Adrenal cortex and medulla

What each part secretes

  • Cortex: mineralocorticoids, chiefly aldosterone, which regulate electrolyte and water balance; glucocorticoids, chiefly cortisol, which drive carbohydrate metabolism and damp inflammation; and small amounts of androgens and estrogens
  • Medulla: epinephrine and norepinephrine
  • The cortex is controlled by ACTH from the pituitary

The syndromes

  • Addison disease: adrenocortical insufficiency with cortical atrophy. Hypotension, weakness, fatigue, loss of appetite and weight, and a characteristic bronzing of the skin. Prognosis is good on steroid replacement
  • Conn syndrome: aldosteronism from excess aldosterone, present in about 0.5 percent of patients with sustained hypertension, usually from a cortical adenoma measuring 0.5 to 3 cm with contralateral adrenal atrophy. Muscle weakness, hypertension, abnormal electrocardiogram
  • Adrenogenital syndrome: excess sex hormones and adrenal androgens, from a tumor or from hyperplasia, producing virilization
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RETROPERITONEUM
Adrenal Masses
UltrasoundRounded solid mass superior to the upper pole of the kidney, separate from renal parenchyma
Suprarenal mass above the upper pole

Tumors

  • Benign nonfunctioning adenoma is the most common primary adrenal tumor
  • The adrenal glands are the fourth most common site in the body for metastasis, after the lung, the liver, and the bones
  • Pheochromocytoma arises from the pheochromocytes of the medulla and secretes epinephrine and norepinephrine in excessive quantities
  • Neuroblastoma is the most common adrenal malignancy of childhood and the most common tumor of infancy, representing about 30 percent of all neonatal tumors

Non neoplastic

  • Adrenal hemorrhage is most common in neonates after a traumatic delivery with stress, asphyxia, or septicemia. The gland may return to normal size with focal areas of calcification
  • Adrenal cysts appear as anechoic lesions with through transmission in the suprarenal location
Trick: A suprarenal mass is not automatically adrenal. Prove it is separate from the kidney, the crus, and the bowel before naming it.
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Card 48  ·  Retroperitoneum: Nodes, Masses & Collections
Front
SITM
RETROPERITONEUM
Lymph Nodes
UltrasoundEcho poor rounded masses along the anterior and lateral margins of the aorta with the vessel displaced anteriorly
Para-aortic lymphadenopathy

Where and how to look

  • The nodes lie along the lateral and anterior margins of the aorta and the IVC, so scan supine or decubitus
  • Always examine in two planes; enlarged nodes should be reproducible in both projections
  • A left coronal view using the left kidney as a window reaches the para-aortic group

The patterns

  • Rounded, focal, echo poor lesions, 1 to 3 cm and larger
  • Confluent echo poor masses, which often displace the kidney laterally
  • A mantle of nodes in the paraspinal location
  • A floating aorta, displaced anteriorly by the enlarged nodes
  • The mesenteric sandwich sign, anterior and posterior nodal masses surrounding the mesenteric vessels

Node or bowel

  • Nodes hold their shape under gentle transducer pressure and transmit sound homogeneously
  • Bowel changes with peristalsis, shows dense central mucosal echoes, and often shadows from air within the wall
Trick: Use color flow before calling a lesion a node. A vessel in cross section looks exactly like one.
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RETROPERITONEUM
Masses & Collections
UltrasoundHypoechoic sheet of tissue enveloping the aorta and IVC anterior to the spine
Retroperitoneal fibrosis around the great vessels

Tumors

  • Lymphoma is the most common primary retroperitoneal tumor
  • Metastatic disease can occur anywhere in the retroperitoneum, arriving hematogenously, through the lymphatics, or by direct extension
  • Evaluate splenic size and the splenic hilum in any patient with lymphadenopathy

Fluid collections

  • Urinoma: a walled off collection of extravasated urine, developing spontaneously or after trauma, surgery, or subacute to chronic urinary obstruction
  • Retroperitoneal hemorrhage: seen with trauma, vasculitis, bleeding diathesis, a leaking aortic aneurysm, or a bleeding neoplasm

Fibrosis

  • Retroperitoneal fibrosis, Ormond disease, is an idiopathic condition characterized by thick sheets of fibrous tissue in the retroperitoneal cavity
  • It encases the great vessels and the ureters, so hydronephrosis is often the presenting finding
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Thyroid & Parathyroid

4 cards. Rate each from cut it to must keep, and note what to cut, add or reword. Highlight any words on a card to comment on them directly.

Card 49  ·  Thyroid & Parathyroid: Normal
Front
SITM
THYROID
Anatomy & Sonographic Appearance
IllustrationRight and left lobes joined by isthmus, trachea medial, CCA and IJV lateral, longus colli posterior
Thyroid gland in the anteroinferior neck

Location & Shape

  • Located in the anteroinferior neck, inferior to the thyroid cartilage
  • Right and left lobes connected across the midline by the isthmus
  • The lobes are normally equal in size, with a wide range of variability; a pyramidal lobe (superior extension of the isthmus) is a normal variant
  • Isthmus normally measures between 2 and 6 mm in the AP dimension

Sonographic Appearance

  • Fine, homogeneous echotexture
  • Slightly more echogenic than the surrounding musculature
  • Thin echogenic thyroid capsule

Transverse Landmarks

  • Trachea in the midline, posterior to the isthmus
  • Common carotid artery and internal jugular vein lateral to each lobe
  • Longus colli muscle posterior to the thyroid
  • Strap muscles (sternohyoid, sternothyroid, thyrohyoid, omohyoid) anterior; sternocleidomastoid anterolateral
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THYROID
Technique, Physiology & Parathyroid
IllustrationSupine patient with pillow under shoulders and neck hyperextended; four parathyroid glands posterior to thyroid
Scanning setup and parathyroid location

Patient & Transducer

  • Supine with a pillow or pad under both shoulders for moderate neck hyperextension
  • High-frequency linear array transducer, 7 to 15 MHz
  • Select the highest frequency that still penetrates
  • Scan each lobe in transverse and sagittal planes

Thyroid Physiology & Labs

  • Follicular cells produce thyroxine (T4) and triiodothyronine (T3); iodine required
  • Parafollicular (C) cells secrete calcitonin
  • TSH from the pituitary regulates thyroid hormone output
  • Labs typically show elevated TSH with low T3 and T4 in primary hypothyroidism, and the opposite pattern in hyperthyroidism

Parathyroid Glands

  • Endocrine glands located on the posterior surface of the thyroid
  • Most people have four parathyroid glands, though 3 to 5 glands is not uncommon
  • Normal parathyroid gland measures about 5 to 6 mm
  • Secrete parathyroid hormone (PTH), the principal regulator of calcium homeostasis
  • Normal glands are usually too small to identify on ultrasound
Trick: Thyroid is more echogenic than the adjacent strap muscles. If the gland looks darker than the straps, think diffuse thyroid disease.
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Card 50  ·  Thyroid: Diffuse Disease
Front
SITM
THYROID
Goiter & Graves Disease
UltrasoundDiffusely enlarged thyroid with markedly increased color Doppler flow (thyroid inferno)
Graves disease with hypervascular gland

Confidence

ConfusedGot it

Shade one more block each time you review.

Goiter

  • Diffuse enlargement of the thyroid gland, with or without palpable nodules
  • Isthmus exceeding 1 cm in the AP plane suggests enlargement
  • Diffusely heterogeneous echotexture; may show focal scarring, ischemia, necrosis, or cyst formation
  • Multinodular goiter is a common cause of diffuse enlargement

Graves Disease

  • Most common cause of hyperthyroidism; autoimmune, more common in women
  • Diffusely enlarged, hyperplastic gland
  • Marked hypervascularity on color Doppler termed the "thyroid inferno"
  • Labs: high T3 and T4, low TSH
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THYROID
Hashimoto Thyroiditis
Heterogeneous micronodular thyroid in Hashimoto thyroiditis
Chronic lymphocytic (Hashimoto) thyroiditis

Hashimoto Thyroiditis

  • Chronic lymphocytic thyroiditis; autoimmune, most common cause of hypothyroidism
  • More common in women
  • Mild enlargement of the gland initially, with later atrophy
  • Diffusely heterogeneous, hypoechoic echotexture
  • Multiple, ill-defined hypoechoic regions separated by echogenic fibrous bands

Clinical Correlation

  • Preexisting Hashimoto disease is a known risk factor for thyroid lymphoma
  • Labs typically show low T3 and T4 with elevated TSH
Trick: Both Graves and Hashimoto can look diffusely hypoechoic. Add color Doppler: Hashimoto vascularity is variable and typically less than the Graves inferno.
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Card 51  ·  Thyroid: Nodules & Parathyroid
Front
SITM
THYROID
Nodules & Papillary Carcinoma
UltrasoundSolitary solid markedly hypoechoic thyroid nodule, taller-than-wide, with internal microcalcifications
Suspicious thyroid nodule

Red Flag Features

  • Taller than wide
  • Microcalcifications
  • Markedly hypoechoic
  • Irregular margins
  • Marked internal flow

Nodule Basics

  • Nodules may be cystic, solid, or complex
  • Simple anechoic cysts and colloid cysts (with echogenic focus and comet-tail) are typically benign
  • Follicular adenoma is the most common benign thyroid neoplasm; well-encapsulated solid mass
  • Any suspicious cystic or complex mass may require FNA biopsy

Suspicious (Malignant) Features

  • Solitary, solid mass that is markedly hypoechoic compared with the gland
  • Taller-than-wide shape
  • Internal microcalcifications (psammoma bodies)
  • Irregular margins
  • Marked internal vascularity

Papillary Carcinoma

  • Most common thyroid malignancy, approximately 70% of thyroid cancers
  • Classically hypoechoic solid mass with microcalcifications
  • May spread to cervical lymph nodes
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PARATHYROID
Parathyroid Adenoma
UltrasoundOval hypoechoic solid mass posterior to the lower pole of the thyroid
Parathyroid adenoma

Parathyroid Adenoma

  • Benign solid mass and the most common cause of primary hyperparathyroidism
  • Appears as a hypoechoic mass adjacent to or posterior to the thyroid gland
  • Usually solitary; most often near the lower pole
  • Normal parathyroid glands are typically not visualized

Primary Hyperparathyroidism

  • Elevated serum calcium
  • Elevated PTH
  • Most often caused by a parathyroid adenoma; less commonly parathyroid hyperplasia or, rarely, parathyroid carcinoma

Secondary Hyperparathyroidism

  • Associated with chronic renal failure and vitamin D deficiency
  • Elevated PTH with low calcium
  • May demonstrate enlargement of all four parathyroid glands
Trick: A hypoechoic mass hugging the posterior thyroid in a patient with high calcium and high PTH is a parathyroid adenoma until proven otherwise.
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Card 52  ·  Thyroid: Carcinoma Subtypes & Neck Masses
Front
SITM
THYROID
Carcinoma
UltrasoundSolid markedly hypoechoic nodule that is taller than wide with punctate echogenic foci
Suspicious thyroid nodule

The suspicious pattern

  • A solid mass that is markedly hypoechoic, with irregular margins, and taller than wide
  • Microcalcifications are tiny punctate echogenic foci under 2 mm, usually without acoustic shadowing
  • Colour Doppler may show increased vascularity with a disorganized internal flow pattern
  • Sonography can demonstrate inflammatory, benign, and malignant conditions but cannot reliably tell them apart, so suspicious nodules go to fine needle aspiration under ultrasound guidance

The subtypes

  • Papillary: the most common, spreads through lymphatics to cervical nodes, associated with microcalcifications
  • Follicular: spreads haematogenously; cytology cannot distinguish adenoma from carcinoma, so it needs excision
  • Medullary: arises from parafollicular C cells, secretes calcitonin, associated with MEN syndromes
  • Anaplastic: elderly patients, rapidly growing, poor prognosis

Thyroid lymphoma

  • Primarily non Hodgkin, and almost always arising in a gland with pre-existing Hashimoto thyroiditis. A large hypoechoic lobulated solid mass with poor internal vascularity, in an older woman with a rapidly growing neck mass
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THYROID
Neck Masses
UltrasoundRounded hypoechoic cervical node with loss of the normal fatty hilum
Abnormal cervical lymph node

Cervical nodes

  • A normal node is oval with a bright fatty hilum and hilar flow
  • Suspicious features are a rounded shape, loss of the hilum, cystic change, calcification, and peripheral rather than hilar vascularity
  • Cervical node metastases are present in 20 to 50 percent of papillary carcinomas at diagnosis
  • A normal node stays under 1 cm in short axis, is oval, and keeps a thin symmetric cortex with hilar flow

Developmental cysts

  • Thyroglossal duct cyst: midline, at or below the hyoid, mostly paediatric with 90 percent found before age 10
  • Branchial cleft cyst: lateral, anterior to the sternocleidomastoid, near the mandibular angle
  • Cystic hygroma: multiloculated, posterior triangle, usually presenting in infancy

Landmarks

  • The longus colli muscle lies posterior to each lobe and is the landmark that keeps a posterior nodule from being called extrathyroidal
  • The isthmus bridges the lobes anterior to the trachea
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Scrotum & Testes

5 cards. Rate each from cut it to must keep, and note what to cut, add or reword. Highlight any words on a card to comment on them directly.

Card 53  ·  Scrotum & Testes: Normal
Front
SITM
SCROTUM
Anatomy
IllustrationTestis with mediastinum, tunica albuginea and vaginalis, epididymal head, body, and tail
Scrotal and testicular anatomy

Testis

  • Paired ovoid organs suspended within the scrotum
  • Covered by the tunica albuginea, a dense fibrous capsule
  • Tunica vaginalis is a double serous layer (parietal and visceral) covering the testis and epididymis; a potential space between the layers is where hydroceles form
  • Mediastinum testis appears as an echogenic band located along the posterolateral aspect of the testis

Epididymis and vas deferens

  • Three parts: head, body, and tail
  • Head lies superior to the upper pole of the testis; body and tail course posteriorly along the testis
  • Echogenicity is similar to or slightly less than the adjacent testis
  • The epididymal tail continues as the vas (ductus) deferens

Scrotal wall and spermatic cord

  • Dartos muscle divides the scrotum into two compartments; the cremaster muscle provides thermoregulation
  • Spermatic cord contents: vas deferens, testicular artery, cremasteric artery, artery to the vas, pampiniform plexus, lymphatics, and nerves

Vascular supply

  • Testicular artery branches into capsular artery, then centripetal artery, then recurrent rami
  • Cremasteric and deferential arteries accompany the testicular artery within the spermatic cord
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Sonographic Technique
UltrasoundTransverse dual image of both testes with color Doppler for side by side comparison
Bilateral comparison view

Transducer

  • High frequency linear array transducer is preferred for scrotal imaging
  • Very high frequency probes (7 to 15 MHz) are typical for smaller superficial structures such as the scrotum

Patient and protocol

  • Patient is imaged supine with the scrotum supported
  • Each testis is evaluated in transverse and sagittal planes
  • Obtain a transverse image of the right and left testes together for side by side comparison in both gray scale and color Doppler
  • Include images of the epididymal head superior to the testis and follow the body and tail posteriorly

Doppler evaluation

  • Color and pulsed Doppler flow within each testicle and epididymis should be symmetric
  • Match color and spectral settings on the contralateral side before comparing
  • Perform the Valsalva maneuver when a varicocele is suspected
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Card 54  ·  Scrotum & Testes: Detailed Anatomy & Cryptorchidism
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SCROTUM
Anatomy
IllustrationTestis with tunica albuginea, mediastinum testis, rete testis, and the epididymal head, body, and tail
Testicular and epididymal anatomy

Coverings and structures

  • The tunica albuginea is the fibrous capsule directly investing the testis; it invaginates to form the mediastinum testis
  • The rete testis sits at the hilum, where the mediastinum resides
  • A potential space lies between the visceral and parietal layers of the tunica vaginalis. This is the space in which a hydrocele, pyocele, or hematocele develops
  • In the adult each testis is about 3 to 5 cm long, 2 to 4 cm wide, and 3 cm high

Epididymis

  • A tubular structure of 6 to 7 cm, beginning superiorly at the head and coursing posterolateral to the testis through body and tail
  • The head is the largest and most consistently visualized portion, isoechoic or slightly hypoechoic to testis with a coarser echotexture

Vessels

  • The right and left testicular arteries arise from the abdominal aorta just below the level of the renal arteries
  • Venous drainage passes through the veins of the pampiniform plexus

Appendages

  • The appendix testis and appendix epididymis sit at the upper pole. Either can torse and mimic torsion, showing a small hypoechoic paratesticular mass with increased peripheral flow
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Cryptorchidism
UltrasoundSmall oval hypoechoic structure within the inguinal canal
Undescended testis in the inguinal canal

Undescended testis

  • Cryptorchidism describes a testis that has not descended into the scrotum and cannot be brought there by external manipulation
  • Most lie in the inguinal canal, where ultrasound finds them readily. An intraabdominal testis is often impossible to locate sonographically and needs CT or MRI
  • The undescended testis is usually smaller and slightly less echogenic than its descended partner

Why it matters

  • Carries 2.5 to 8 times the malignancy risk of a normally descended testis
  • Also associated with infertility
  • Surgical treatment, freeing the testis and implanting it in the scrotum, is orchiopexy. It does not remove the malignancy risk

Tubular ectasia

  • Tubular ectasia of the rete testis is an uncommon benign condition, associated with a spermatocele, an epididymal or testicular cyst, or other epididymal obstruction on the same side
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Card 55  ·  Scrotum & Testes: Pathology
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SCROTUM
Inflammatory & Torsion
Marked epididymal hyperaemia on colour Doppler
Epididymitis with marked hyperaemia

Epididymitis and epididymo-orchitis

  • Most common cause of acute scrotal pain in adults
  • Inflamed epididymis appears enlarged, hypoechoic, or heterogeneous
  • Hyperemic flow within the epididymis and/or testis on color Doppler
  • Associated findings include a hypoechoic testis with orchitis, thickened scrotal wall, and reactive hydrocele

Testicular torsion

  • Most common cause of acute scrotal pain in adolescents
  • Early stages may show a normal sonographic appearance
  • After 4 to 6 hours the testis becomes swollen and hypoechoic
  • Color Doppler shows decreased or absent intratesticular flow compared with the contralateral testis
  • Paratesticular flow may be increased around the abnormal testis
Trick: Always set color Doppler on the asymptomatic side first, then apply identical settings to the painful side so a true flow difference is not hidden by scanner adjustments.
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Fluid, Vascular & Mass
UltrasoundAnechoic fluid surrounding testis, serpiginous veins over 3 mm, hypoechoic intratesticular mass, echogenic foci
Extratesticular and intratesticular findings

One Root, Four Words

-celeswelling or hernia
  • hydro water, so hydrocele is clear fluid
  • hemato blood, so hematocele is blood
  • pyo pus, so pyocele is infection
  • varico dilated vein, so varicocele is veins

Hydrocele, hematocele, and pyocele

  • Hydrocele is a fluid filled collection located between the two layers of the tunica vaginalis, sonographically anechoic surrounding the testis
  • Hematocele = blood, pyocele = pus, in the same potential space; usually complex with septations and debris

Varicocele

  • Caused by incompetent valves within the pampiniform plexus
  • Veins measuring 3 mm or larger in diameter are considered varicose
  • Occurs most often on the left side
  • Distension increases with the Valsalva maneuver

Testicular carcinoma

  • Most testicular tumors are well defined hypoechoic intratesticular masses
  • Larger tumors may be poorly marginated or appear heterogeneous

Testicular microlithiasis

  • Multiple bright, nonshadowing echogenic foci scattered throughout the testis
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Card 56  ·  Scrotum & Testes: Testicular Tumors
Front
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SCROTUM
Germ Cell Tumors
UltrasoundHomogeneous hypoechoic mass replacing part of the testicular parenchyma
Seminoma

The governing rule

  • Extratesticular masses are usually benign; intratesticular masses are more likely malignant
  • That single distinction drives the whole scan, so establish whether a mass is inside or outside the tunica albuginea first
  • Testicular cancer is uncommon overall but is the most common malignancy in men aged 15 to 35

Germ cell tumours

  • Testicular tumours divide into germ cell and non germ cell types
  • Germ cell tumours are associated with elevated human chorionic gonadotropin and alpha fetoprotein
  • Seminoma: homogeneous, hypoechoic, with a smooth border
  • Embryonal cell carcinoma: heterogeneous and less well circumscribed, with areas of increased echogenicity from calcification, haemorrhage, or fibrosis, and possible cystic components
  • Teratoma: heterogeneous with well defined borders, and may contain dense foci that shadow
  • Germ cell tumours are about 95 percent of testicular tumours and are usually malignant. Non germ cell (stromal) tumours are generally benign
  • Teratomas tend to be benign in children and malignant in adults
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Other Tumors
UltrasoundMultiple small bright nonshadowing foci scattered evenly through the testis
Testicular microlithiasis

Secondary tumours

  • Malignant lymphoma makes up 1 to 7 percent of testicular tumours and is the most common bilateral secondary testicular neoplasm in men over 60
  • Leukaemic infiltration is the equivalent in children
  • Bilateral or diffuse involvement in an older man points away from a primary germ cell tumour

Microlithiasis

  • Multiple bright, nonshadowing foci scattered throughout the testis
  • The absence of shadowing is what separates it from coarse calcification
  • More than five microliths on any single image is considered abnormal
  • Associated with cryptorchidism, Klinefelter syndrome, infertility, testicular atrophy, and an increased risk of germ cell tumour, so annual follow up is advised

Scanning for a tumour

  • Compare both testes in the same image at identical settings, since a subtle echogenicity difference is easier to see side by side than alone
  • Any focal intratesticular lesion is treated as malignant until proven otherwise
Trick: Inside the testis, assume malignant. Outside it, assume benign. Then look for what disproves you.
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Card 57  ·  Scrotum & Testes: Extratesticular Masses & Fluid
Front
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SCROTUM
Fluid Collections
Anechoic fluid surrounding the testis
Hydrocele

The tunica vaginalis space

  • Hydrocele: serous fluid, the most common cause of painless scrotal swelling. May be idiopathic but is commonly associated with epididymo-orchitis and torsion
  • Pyocele: a collection of pus, from untreated infection or an abscess rupturing into the space
  • Hematocele: blood, usually post traumatic, appearing complex with septations as it organizes

Varicocele

  • Abnormal dilatation of the veins of the pampiniform plexus within the spermatic cord
  • Usually caused by incompetent venous valves within the spermatic vein
  • Dilated tubular structures over 2 mm that enlarge with Valsalva and standing
  • More common on the left. A new right sided varicocele raises the possibility of a retroperitoneal mass
  • The left side predominates because the left spermatic vein joins the left renal vein at a steep angle, and that vein can be compressed between the aorta and the SMA
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Extratesticular Masses
Anechoic cyst at the epididymal head
Epididymal cyst at the head

Cysts

  • Cysts are benign fluid collections that may lie within the testis or in the extratesticular structures. Most scrotal cysts are extratesticular
  • Spermatocele: contains spermatozoa, arises at the epididymal head, and may show low level internal echoes
  • Epididymal cyst: contains clear serous fluid and may arise anywhere along the epididymis

Solid extratesticular lesions

  • Adenomatoid tumour: a benign solid extratesticular mass arising in the epididymis
  • Sperm granuloma: a chronic inflammatory reaction to extravasation of spermatozoa, seen most often after vasectomy

Hernia

  • Bowel, omentum, or other structures may herniate into the scrotum
  • Peristalsis within the scrotal contents settles the diagnosis immediately
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The 18 digital only cards

The four topics you said could skip the printed deck: contrast agents, ultrasound guided intervention, emergent procedures, and the transplant patient. Same format and the same authoring depth as the printed cards. Where these live is still open, so rate them the same way and say whether you want them printed after all.

Card 1  ·  Contrast Agents: Fundamentals
Front
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CONTRAST
Agent Properties
IllustrationCross section of a gas microbubble encapsulated in a stabilizing outer shell, drawn smaller than a red blood cell
Encapsulated microbubble UCA

What a UCA is

  • Ultrasound contrast agents are gas microbubbles encapsulated by an outer shell for stability
  • Given intravenously to evaluate vessels, blood flow, tumors, and solid organs
  • Enhance ultrasound signals by adding acoustic scatterers to the bloodstream

Clinical requirements

  • Nontoxic, with microbubbles less than 8 microns so they traverse the pulmonary capillary beds
  • Stable enough to provide multiple recirculations
  • Shell products are metabolized or eliminated by the body and the gas is exhaled

Vascular vs tissue specific

  • Vascular or blood pool agents remain in the vascular space until the microbubbles rupture
  • Tissue specific agents are taken up by target tissues such as the reticuloendothelial system of the liver and spleen
  • Sonazoid uses perfluorobutane in a lipid shell, is phagocytosed by Kupffer cells, and can behave as both a vascular and a tissue specific agent
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CONTRAST
CEUS Imaging
UltrasoundSide by side gray scale and contrast harmonic images of a liver mass, with microbubbles brightening the lesion on the contrast panel
Contrast harmonic imaging display

Contrast harmonic imaging

  • Harmonic imaging uses the same broadband transducer but receives echoes at the second harmonic, twice the transmit frequency
  • Microbubbles oscillate in the acoustic field and return energy at fundamental, harmonic, and subharmonic frequencies
  • Contrast harmonic imaging preferentially displays microbubble echoes while suppressing tissue echoes
  • Avoids Doppler angle dependence and color blooming artifacts

Mechanical index

  • Acoustic pressure in the field can destroy microbubbles and shorten the duration of enhancement
  • The mechanical index is the standard measure of acoustic output
  • CEUS presets use low MI values, generally below 0.2, to preserve microbubbles during continuous imaging

Acoustic emission

  • With enough energy the microbubbles first oscillate and then rupture
  • Rupture produces random Doppler shifts seen as a transient color mosaic, termed acoustic emission
  • With a tissue specific agent, masses that have destroyed Kupffer cells appear as color free areas against the enhanced parenchyma

Preferred approach

  • Contrast specific imaging modes replace conventional color flow imaging when using UCAs
  • Intermittent imaging pauses transmission at set intervals to preserve microbubbles for late washout assessment
Trick: Vascular agents stay in the pipes. Tissue specific agents park in the tissue and get read on the delayed phase.
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Card 2  ·  Contrast Agents: Hepatic Applications
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CONTRAST
Hepatic CEUS
IllustrationTimeline of hepatic contrast phases with arterial enhancement at 25 seconds, portal venous enhancement at 37 seconds, and late parenchymal blush at 71 seconds
Phases of hepatic enhancement

Vascular phases

  • Arterial phase, the hepatic arteries enhance first, roughly 25 seconds after intravenous injection
  • Portal venous phase, contrast fills the portal vein, roughly 37 seconds after injection
  • Late phase, parenchymal blush from flow in the hepatic capillaries, roughly 71 seconds after injection
  • With a tissue specific agent, a delayed phase reflects microbubbles phagocytosed by the reticuloendothelial system

Why use CEUS

  • B mode is limited for lesions less than 10 mm, isoechoic lesions, or peripheral lesions, particularly in obese patients and diffuse liver disease
  • Characterization of hepatic tumors requires evaluating the enhancement kinetics of the mass
  • Improves detection of slow portal flow in portal hypertension
  • Used to assess flow through transjugular intrahepatic portosystemic shunts

CEUS LI-RADS

  • The ACR CEUS LI-RADS system defines lesion enhancement in the arterial phase and washout kinetics relative to the surrounding liver
  • Classification is used to categorize the risk of malignancy
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CONTRAST
Focal Lesion Patterns
UltrasoundTwo panel CEUS comparison of a hyper enhancing hepatocellular carcinoma in the arterial phase and washout in the portal venous phase
HCC enhancement pattern

Hepatocellular carcinoma

  • Hyper enhancement in the early arterial phase
  • Washout of contrast in the later portal venous phase
  • With a reticuloendothelial system specific agent, HCC is hypoechoic on delayed imaging because the tumor lacks Kupffer cells

Focal nodular hyperplasia

  • Central feeding artery with spoke wheel radiating branches
  • Isoechoic on delayed imaging with a tissue specific agent because FNH contains abundant Kupffer cells

Cavernous hemangioma

  • Peripheral globular enhancement in the arterial phase
  • Progressive centripetal filling without washout, lasting 5 to 7 minutes
  • Classified as definitely benign, LR-1, on CEUS LI-RADS

Liver metastases

  • Vascularity depends on the primary cancer, so lesions may be hyper or hypovascular
  • Delayed phase often shows an echogenic rim around the tumor
  • Washout less than 60 seconds after injection is often indicative of metastatic disease
  • Rim hyper enhancement in the arterial phase or early washout classifies the lesion LR-M
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Card 3  ·  Contrast Agents: Renal, Splenic & Other
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CONTRAST
Renal and Splenic
UltrasoundContrast harmonic image of a cystic renal mass with fine septations and no internal enhancement
Indeterminate renal cyst on CEUS

Renal masses

  • An ideal patient population, as CEUS avoids nephrotoxic MRI or CT contrast when renal function is compromised
  • High accuracy for characterization of indeterminate renal masses, with renal cell carcinoma ruled out in a large percentage
  • Improves visualization of the normal renal vasculature and of lesions that distort it
  • Useful for guiding and monitoring locoregional ablation of renal cell carcinoma and for detecting residual or recurrent tumor

Renal artery stenosis

  • Main renal arteries are retroperitoneal and often difficult to evaluate, particularly in obese patients
  • Accessory or duplicate renal arteries can be missed on conventional ultrasound
  • CEUS is used as a salvage tool when conventional renal artery stenosis studies are nondiagnostic

Splenic applications

  • Higher sensitivity than CT or PET for detecting splenic involvement in Hodgkin lymphoma in a published prospective series
  • Sensitivity for parenchymal splenic injury rose from 63 percent on baseline ultrasound to 89 percent after CEUS
  • Attractive in pediatric patients because it avoids ionizing radiation from CT
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CONTRAST
Non hepatic Uses
UltrasoundDual display of an aortic graft with contrast tracking into the aneurysm sac, consistent with an endoleak
Endoleak after EVAR

Organ transplants

  • Conventional ultrasound cannot reliably detect flow at the microvascular level
  • CEUS improves detection of ischemic regions in renal and pancreatic grafts
  • Differentiates parenchymal abnormalities in renal transplants such as acute tubular necrosis from other causes
  • Investigated for detection of early organ rejection

Endovascular aneurysm repair

  • Surveillance after endovascular aneurysm repair continues for months or years to detect endoleaks
  • A single UCA injection provides several minutes of enhancement to assess both fast flowing and slow flowing endoleaks
  • An advantage over contrast enhanced CT, which uses only one or a few phases to limit ionizing radiation

Pancreatic masses

  • Arrival time and time to peak were significantly longer in pancreatic ductal adenocarcinoma than in focal inflammatory masses in a published series
  • Perfusion patterns on CEUS help separate PDAC from chronic pancreatitis masses

Vesicoureteral reflux

  • Lumason is FDA approved for ultrasonography of the urinary tract to evaluate suspected or known vesicoureteral reflux in pediatric patients
  • An alternative to voiding cystourethrography that avoids ionizing radiation in a vulnerable population
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Card 4  ·  Interventional: Fundamentals & Approach
Front
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INTERVENTION
Fundamentals
IllustrationTransducer over the abdomen with the needle entering from the short end of the probe aligned along the sound beam toward a target mass
Real time needle guidance to a target mass

Advantages

  • Continuous real time visualization of the needle, allowing adjustment as the needle advances
  • Different patient positions and approaches: decubitus or oblique can shorten the path and open a safe window
  • Portable, no radiation, single breath hold biopsies, and shorter procedure times

Approach choices

  • A subcostal approach for masses at the dome of the liver uses a steep cephalad angle to reduce the risk of pneumothorax
  • When a mass is isoechoic, look for indirect signs of it: displaced vessels, capsule bulges, or tumour vessels

Limitations

  • Bowel gas may obscure the target and may move during the procedure
  • Needle tip visualization drops when the needle deviates out of the beam plane
Trick: Isoechoic and hidden equals fusion or contrast. Bowel in the way equals reposition or reschedule.
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INTERVENTION
Indications & Contraindications
UltrasoundRetroperitoneal lymph node surrounded by vessels with no safe corridor for a needle
A vessel encased node lacks a safe pathway

Common indications

  • Confirm if a mass is benign, malignant, or infectious
  • Differentiate metastatic disease from a second primary in a patient with a known cancer
  • Differentiate recurrent tumour from post surgical or therapy scarring

Non mass indications

  • Parenchymal sample for fatty liver, hepatitis, or renal failure staging
  • Determine the cause of rejection in a transplanted organ

Contraindications

  • Uncorrectable bleeding disorder
  • Lack of a safe needle pathway around vessels or bowel
  • Uncooperative patient who cannot hold still or control breathing, raising complication risk for the patient and needle stick risk for the team
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Card 5  ·  Interventional: Coagulation & Complications
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INTERVENTION
Coagulation Labs
IllustrationDiagram of the coagulation cascade with intrinsic and extrinsic pathways converging on the common pathway
Bleeding time tests before a biopsy

Which tests

  • Bleeding time studies are the one lab set reviewed before most ultrasound guided procedures
  • Prothrombin time (PT), partial thromboplastin time (PTT), and platelet count together evaluate the intrinsic, extrinsic, and common pathways of the coagulation cascade

Normal values

  • PT normal 10 to 13 seconds, evaluates the extrinsic pathway and reflects Coumadin effect
  • PTT normal 30 to 45 seconds, evaluates intrinsic and common pathways and reflects heparin effect
  • International normalized ratio (INR) standardizes PT across labs; a value less than 1.4 is needed for a safe procedure

Exceptions

  • INR and PT are not used on patients with liver disease or on heparin
  • Patients with a coagulopathy may need a platelet transfusion just before and during the procedure
  • Some departments waive hemostatic testing for low bleeding risk taps such as thyroid, neck node, or prostate biopsies
Trick: Heparin 4 to 6 hours, Coumadin and aspirin 5 days. INR under 1.4, PT 10 to 13, PTT 30 to 45.
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INTERVENTION
Anticoagulants & Risks
UltrasoundColor Doppler over a native kidney biopsy tract showing a bright vascular jet exiting the parenchyma
Active post biopsy bleed as a color Doppler jet

Hold times before biopsy

  • Heparin: 4 to 6 hours off
  • Coumadin: 5 days off
  • Aspirin: 5 days off, though hold times vary by centre, so confirm the local guideline

Minor complications

  • Post procedural pain or discomfort and hematoma
  • Vasovagal reaction with pallor, sweating, faintness, nausea, or syncope; place the patient in Trendelenburg or elevate the feet

Serious complications

  • Hemorrhage, pneumothorax, pancreatitis, biliary leak, peritonitis, infection, and possibly death
  • Tumour seeding of the needle track, estimated at about 1 in 20,000 patients
  • Scan after every pass with gray scale and color Doppler; apply transducer pressure over an active bleed
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Card 6  ·  Interventional: Guidance & Needle Tip
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INTERVENTION
Guidance Methods
IllustrationTwo panels: an in-plane free hand approach with the needle shaft along the sound beam, and an out-of-plane approach where only the tip crosses the beam as a bright echo
In-plane and out-of-plane free hand approaches

In-plane free hand

  • Needle enters from the short end of the transducer so the shaft can be seen advancing through the sound beam
  • If the tip disappears, reposition the transducer to realign with the needle path

Out-of-plane free hand

  • Needle enters the long side of the transducer at a perpendicular angle and appears as a bright echo only when the tip crosses the beam
  • Favoured for superficial work such as intravenous line placement, but the target can be missed if the needle drifts even slightly off perpendicular

Needle guide

  • Bracket attaches to the transducer and the predicted needle path is shown as one line or as two parallel lines on the screen
  • Confirm the angle set on the guide matches the angle on the screen, or the needle will appear to deviate
  • Guides speed the learning curve, keep multiple passes through the anesthetized channel, and open access to deep retroperitoneal and pleural based masses
Trick: In plane sees the shaft. Out of plane sees only the tip. A guide draws you the line.
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INTERVENTION
Tip & Deviation
UltrasoundSonogram of a biopsy needle with a scored echogenic tip appearing as a bright dot inside a hypoechoic mass
Echogenic tip inside a hypoechoic target

Why the tip disappears

  • The needle can cross the sound beam at an angle, so part of the shaft is in the beam while the tip has already passed through it
  • Hyperechoic masses hide the tip; hypoechoic masses show it well; echogenic tip needles and larger gauge needles reflect more brightly

Tricks to find the tip

  • Bob the needle up and down, or jiggle the stylet inside the needle
  • Angle the transducer superiorly and inferiorly in small motions to find a needle bent out of plane
  • Turn on harmonics or compound imaging, or as a last resort withdraw and reinsert while watching tissue displacement

Handling deviation

  • Overcorrect by moving the transducer more lateral or medial so the projected path intersects the mass
  • Verify the guide angle, the insert size, and that the guide exit sits against the skin
  • A 20 gauge needle bends less than a 22 gauge; inserting the needle bevel up reduces tissue impedance
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Card 7  ·  Interventional: FNA, Core & Drainage
Front
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INTERVENTION
Fine-Needle Aspiration
IllustrationThree FNA tip styles labelled Chiba, Franseen, and spinal, with a colour coded hub row showing 25 blue, 22 black, 20 yellow, 18 pink
FNA tip styles and universal hub colours

FNA needles

  • Fine-needle aspiration (FNA) uses thin gauge needles from 20 to 25 gauge with a cutting tip such as Franseen, Chiba, or spinal
  • The higher the gauge number, the smaller the inner diameter: a 20 gauge is 0.6 mm, an 18 gauge is 0.8 mm
  • Universal hub colour code: 25 gauge blue, 22 gauge black, 20 gauge yellow, 18 gauge pink

Technique

  • Capillary action: a steady, quick up and down motion after the stylet is removed obtains cells by scraping or cutting
  • The physician covers the open hub with a thumb as the needle is withdrawn, so cells are not sucked back into the body

Advantages

  • The thin diameter allows safe passage through the gastrointestinal tract and near vascular structures
  • FNA with onsite cytopathology helps confirm diagnostic material and minimizes the number of passes
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INTERVENTION
Core Biopsy & Drainage
UltrasoundSonogram of a needle tenting the Glisson capsule before the biopsy gun is fired
Tenting of Glisson capsule during core placement

Core biopsy

  • Core biopsy uses an automated spring loaded biopsy gun with a 14 to 20 gauge needle to obtain a core of tissue for histology
  • Throw length is the distance the cutting needle advances when fired, ranging from 10 to 23 mm; pick a throw that will not exit the back wall of the mass
  • Tenting is the needle pushing the capsule without piercing it; reposition or fire so the sample is captured

Fluid taps

  • Ascites and pleural fluid usually drain free hand; use a needle guide when the pocket is small, loculated, or unsafe
  • Needle gauge follows fluid viscosity: 20 to 22 gauge for a small sample, 16 to 18 gauge for viscous or infected fluid
  • A centesis catheter with side holes and a 1 litre vacuum bottle drains large volumes

Large volume paracentesis

  • Draining more than 4 to 6 litres puts the patient at risk of electrolyte imbalance, hypovolemia, hypotension, and hepatorenal syndrome
  • Intravenous albumin is usually given when more than 5 litres are removed
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Card 8  ·  Interventional: Liver, Kidney & Transplant
Front
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INTERVENTION
Liver Biopsy
UltrasoundSubcostal window on the right lobe with the needle angled cephalad toward a dome lesion, avoiding the pleura
Subcostal approach for a dome liver mass

Indications

  • Characterize masses such as metastases, hepatocellular carcinoma, benign lesions, or abscesses
  • Sample parenchyma for hepatitis, cirrhosis, fatty liver, or unexplained elevated liver function tests
  • Elevated alpha-fetoprotein (AFP) with a hypoechoic nodule in a cirrhotic liver: biopsy to differentiate hepatocellular carcinoma from a regenerating nodule

Approach

  • A subcostal approach is preferred to avoid pneumothorax and to spare intercostal arteries and nerves
  • Reposition into decubitus or oblique to shorten the path and roll the liver into a subcostal window

Complications

  • Pneumothorax with masses near the dome of the liver
  • Bile leak and hematoma
Trick: Cirrhosis plus rising AFP plus a hypoechoic nodule. Biopsy to sort HCC from a regenerating nodule.
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INTERVENTION
Kidney & Transplant
UltrasoundProne image of the left kidney with an 18 gauge core needle at the lower pole capsule and color Doppler check of the needle track
Native left kidney core at the lower pole

Native kidney

  • Parenchymal core is the common renal biopsy, ordered for rising blood urea nitrogen and creatinine
  • The left kidney is preferred over the right because the spleen sits well above it, giving a safer approach
  • Patient prone, lower pole, usually an 18 gauge core; the tip is placed on the capsule so cortical tissue is sampled

Renal transplant

  • Biopsy the upper pole to avoid lacerating the main renal vessels and ureter
  • Obtain a baseline color Doppler image of the entire kidney at the end, since arteriovenous fistula and pseudoaneurysm can follow

Complications

  • Native kidney: perinephric hematoma and hematuria; fresh hematomas are echogenic
  • Transplant: hematoma, hematuria, pseudoaneurysm, and arteriovenous fistula

Post biopsy

  • Press over the bleed with the transducer for 5 to 10 minutes; if bleeding cannot be stopped, contact interventional radiology
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Card 9  ·  Emergent: FAST Exam
Front
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EMERGENT
Protocol
IllustrationFour FAST windows on a supine trauma patient: subxiphoid pericardial view, right upper quadrant, left upper quadrant, and suprapubic pelvic view.
The four FAST windows

Goal of FAST

  • Focused survey of abdomen, pelvis, and pericardium for free fluid or pericardial fluid
  • An extension of the physical examination of the trauma patient
  • Directs transfer to the operating room, CT scanner, or angiography suite

Survey windows

  • Perihepatic and hepatorenal space in the right upper quadrant
  • Perisplenic in the left upper quadrant
  • Pelvis and cul-de-sac behind the distended bladder
  • Pericardium from the subcostal window

Technique

  • Patient supine, transducer choice by body habitus
  • Fill the empty bladder with 200 to 300 mL of sterile saline through a Foley catheter for the pelvic view
  • Begin subxiphoid, angled cephalic toward the four chamber view of the heart
  • Sweep RUQ diaphragm, subhepatic space, right kidney, and right flank
  • Then LUQ diaphragm, spleen, left kidney, and left flank
  • A rapid survey completes in under 4 minutes
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EMERGENT
Findings & Pitfalls
UltrasoundAnechoic fluid tracking between the right lobe of the liver and the right kidney in Morison's pouch.
Free fluid in Morison's pouch

Free fluid look

  • Usually represents hemoperitoneum but may also be bowel content, urine, bile, or ascites
  • Hypoechoic or hyperechoic with scattered internal echoes, conforming to the space it fills
  • Collects in the most dependent area of the abdomen

Sites of pooling

  • Morison's pouch is the most common site regardless of injury location
  • The pelvis is next, centrally in the pouch of Douglas or laterally in the paravesical space
  • Massive bleeding floats the intraperitoneal organs in fluid

Parenchymal injury

  • Liver lacerations or contusions are more easily detected than any other visceral abdominal injury
  • Hematomas begin hypoechoic or echogenic, then turn anechoic with hemolysis
  • A splenic subcapsular hematoma appears as fluid along the splenic capsule

Pitfalls

  • Ultrasound may miss injuries to the diaphragm, pancreas, adrenal gland, and some bowel
  • Obesity and subcutaneous air limit the views
  • Isolated cul-de-sac fluid in a reproductive age woman is likely physiologic
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Card 10  ·  Emergent: Pericardial Effusion & Tamponade
Front
SITM
EMERGENT
Cardiac Windows
IllustrationSubcostal four chamber view of the heart in a hypotensive patient with an anechoic collection around the ventricles.
Subcostal view for pericardial fluid

Emergent goal

  • The primary application of cardiac ultrasound in the ED is to rule out pericardial effusion or to evaluate cardiac function in sudden cardiac arrest
  • Body habitus and underlying disease limit accessibility
  • Pulmonary hyperinflation obscures parasternal windows but usually spares apical and subcostal windows

Views to obtain

  • Subcostal four chamber, angled cephalic from the epigastrium
  • Parasternal long axis
  • Parasternal short axis
  • Apical four chamber

Where fluid sits

  • Fluid initially collects dependently
  • In parasternal long axis, fluid sits within the pericardial sac beyond the epicardial border of the left ventricle
  • As it grows it becomes circumferential, reflecting off the great vessels
  • Assess the inferior vena cava for dilation without respiratory collapse
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EMERGENT
Size & Tamponade
UltrasoundApical four chamber view of a large pericardial effusion with diastolic collapse of the right ventricular free wall.
Right heart collapse in tamponade

Effusion appearance

  • Anechoic or hypoechoic fluid within the pericardial space
  • Inflammatory, malignant, or hemorrhagic effusions may look complex and echogenic
  • Acute hemopericardium with clot can appear isoechoic to the myocardium

Size in diastole

  • Small: under 1 cm between the epicardium and the posterior fluid border, seen only posteriorly
  • Moderate: 1 to 2 cm, usually circumferential, not extending beyond the atrial appendage
  • Large: over 2 cm in diastole

Signs of tamponade

  • Diastolic collapse of the right atrium or right ventricle with a moderate to large effusion
  • Inferior vena cava dilation without respiratory collapse
  • Pulsus paradoxus on clinical exam
  • A small rapid effusion may tamponade, while large slow effusions may be tolerated

Pleural pitfall

  • Pericardial fluid sits anterior to the descending aorta and pleural fluid sits posterior to it
Trick: Small under 1 cm, moderate 1 to 2 cm, large over 2 cm, all measured in diastole.
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Card 11  ·  Emergent: Aortic Dissection
Front
SITM
EMERGENT
Etiology & Sites
IllustrationThe three common sites of aortic dissection: at the root, at the level of the left subclavian artery, and confined to the ascending aorta.
Common dissection sites

Definition

  • A propagating intramural hematoma dissects along the vessel, stripping the intima and part of the media
  • Blood surges into the media, separating intima from adventitia, forming a false lumen
  • Blood in the false lumen can reenter the true lumen anywhere along its course

Causes

  • Hypertension in 70 to 90 percent
  • Marfan syndrome in 16 percent
  • Pregnancy, aortic stenosis, coarctation, trauma, and iatrogenic causes such as catheterization or valve replacement

Location distribution

  • About 70 percent are in the ascending aorta
  • 10 to 20 percent in the aortic arch
  • About 20 percent in the abdominal aorta
  • Most propagate distally into the iliac vessels

Presentation

  • Sudden severe tearing chest pain radiating to the arms, neck, or back
  • Anterior thoracic pain suggests a proximal site, and interscapular pain suggests distal
  • Absent pulses in an arm or leg point to subclavian or iliac involvement
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EMERGENT
Sonographic Findings
UltrasoundLongitudinal image of the abdominal aorta with an echogenic intimal flap dividing true and false lumens.
Intimal flap in the aorta

Modality choice

  • MRI or contrast enhanced CT is the imaging of choice in acute dissection because time is of the essence
  • Transesophageal echocardiography is done by cardiology when the dissection is ascending
  • Abdominal ultrasound can be requested in the stabilized patient with suspected abdominal extension

Classic sign

  • Echogenic intimal membrane at the site of the dissection
  • The membrane in the aorta or iliac arteries moves with arterial pulsations when both lumens are patent
  • A thick membrane with a thrombosed lumen may not move

Color Doppler

  • Slow flow in both true and false lumens
  • Flow in the false lumen is decreased or reversed
  • Follow the flap and clot into the iliac, celiac, and superior mesenteric arteries

Pseudodissection

  • Turbulent color flow around a hypoechoic thrombus at the outer aortic margin with an echogenic laminated clot
  • No intimal flap is present
Trick: Moving flap means true dissection. Clot without a flap means pseudodissection.
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Card 12  ·  Emergent: Scrotal Trauma & Torsion
Front
SITM
EMERGENT
Protocol
IllustrationSide by side color Doppler comparison of both testes in the transverse plane with identical settings.
Compare both testes with color Doppler

Two emergencies

  • Rupture of the testis from trauma is a surgical emergency requiring prompt diagnosis
  • Torsion of the spermatic cord is a surgical emergency and images should be obtained as soon as possible
  • Torsion follows abnormal mobility of the testis within the scrotum

Rupture salvage clock

  • Trauma may follow a motor vehicle accident, an athletic injury, a direct blow, or a straddle injury
  • Surgery within 72 hours saves at least 90 percent of testes
  • Salvage falls to 45 percent after 72 hours

Torsion patient

  • Torsion is more frequent in the adolescent and young adult
  • Sudden onset of pain and swelling on the affected side

Scanning

  • High frequency linear transducer with gentle contact over a painful, swollen scrotum
  • Compare both testes in grey scale and with color Doppler
  • Image both sides with identical settings for a valid perfusion comparison
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EMERGENT
Findings
UltrasoundColor Doppler shows absent perfusion in the symptomatic left testis with normal flow in the right.
Absent perfusion on the symptomatic side

Rupture signs

  • Focal alteration of the testicular parenchymal pattern
  • Interruption of the tunica albuginea
  • Irregular testicular contour
  • Scrotal wall thickening
  • Hematocele within the tunica vaginalis

Trauma fluids

  • Hydrocele and hematocele are both complications of trauma
  • Hematoceles contain blood and also appear with advanced epididymitis or orchitis

Torsion by time

  • Early: the testis may still look normal and homogeneous
  • 4 to 6 hours: swollen and hypoechoic, with lobes standing out from interstitial and septal edema
  • After 24 hours: heterogeneous from hemorrhage, infarction, necrosis, and vascular congestion
  • The epididymal head enlarges and may look hypoechoic or heterogeneous

Doppler decides

  • Absent perfusion in the symptomatic testis with normal perfusion on the other side is diagnostic of torsion
Trick: Compare both sides with identical Doppler settings. Absent flow against normal flow on the other side is the answer.
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Card 13  ·  Transplant: Liver Anatomy and Approach
Front
SITM
TRANSPLANT
Anatomy
IllustrationOrthotopic liver transplant with a Mercedes sign incision and the suprahepatic IVC, portal vein, hepatic artery, and bile duct anastomoses labeled.
Liver allograft anastomoses

Placement

  • Bilateral subcostal incisions extend to the xiphoid, the Mercedes sign scar
  • The diseased liver is removed and the donor liver is placed orthotopically in the anhepatic bed
  • In a living donor recipient only the right hepatic lobe is transplanted, so no left lobe and no gallbladder are imaged

Anastomoses

  • Suprahepatic IVC sewn end to side onto the recipient hepatic vein trunk, and the portal vein sewn end to end
  • Common hepatic arteries joined end to end and the donor gallbladder is removed at surgery
  • Bile duct joined duct to duct over a stent, or a Roux-en-Y limb in PSC and retransplant patients

How to scan

  • Image with a 2.5 to 5.0 MHz curvilinear transducer with the patient fasting 4 to 6 hours
  • Compare the right hepatic lobe with the right renal cortex for echogenicity
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TRANSPLANT
Normal Doppler
UltrasoundSpectral Doppler of a transplant hepatic artery with a sharp systolic upstroke and continuous diastolic flow above baseline.
Normal hepatic artery in the transplant

Hepatic artery

  • Sharp systolic upstroke with continuous diastolic flow above baseline, a low-resistance waveform
  • Peak velocities should stay below 200 cm per second
  • Normal resistive index ranges from 0.50 to 0.70

Portal vein

  • Hepatopetal, continuous, with minimal respiratory change
  • Turbulence or a doubling or tripling of velocities between segments is abnormal

IVC and hepatic veins

  • Phasic bidirectional waveform tracking the cardiac cycle
  • The left hepatic vein appears more pulsatile because it sits closer to the heart

Doppler pearl

  • Keep the angle parallel to the vessel and below 60 degrees to avoid falsely elevated velocities
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Card 14  ·  Transplant: Liver Vascular Complications
Front
SITM
TRANSPLANT
Hepatic Artery
UltrasoundTardus parvus arcuate hepatic artery waveform with a dampened upstroke and a low resistive index.
Hepatic artery stenosis with tardus parvus

HA thrombosis

  • Most common vascular complication after liver transplant
  • Occurs in 4 to 12 percent of adults and about 42 percent of children, between postoperative days 15 and 132
  • Absent color and no spectral flow; echogenic thrombus may fill the lumen
  • The HA is the sole blood supply to the biliary ducts, so untreated thrombosis leads to biliary ischemia and often retransplantation

HA stenosis

  • Seen in 2 to 11 percent of transplants, most often at the anastomosis
  • Tardus parvus arcuate waveform with an RI below 0.50 and a peak velocity greater than 200 cm per second
  • In the first 72 hours an RI above 0.80 from postoperative edema is common and usually resolves within a few days

Pitfall

  • A tortuous HA can give a falsely elevated velocity, and slow flow from low cardiac output can mimic thrombosis
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TRANSPLANT
Veins and Pseudoaneurysm
UltrasoundMain portal vein filled with echogenic thrombus and no color flow at the transplant anastomosis.
Portal vein thrombus in the transplant

Portal vein

  • Stenosis occurs in about 1 percent and thrombosis in about 3 percent, usually at the anastomosis
  • Stenosis shows color and spectral aliasing with roughly a 3 to 1 velocity ratio across the anastomosis
  • Fresh thrombus is echogenic; occlusive thrombus abolishes color and spectral flow

IVC and hepatic veins

  • Combined complication rate is less than 1 percent, most often at the anastomosis or from suprahepatic caval kinking
  • Stenosis produces a monophasic, dampened hepatic vein waveform with color aliasing and turbulence
  • Chronic IVC stenosis is more common in retransplant and pediatric patients

Pseudoaneurysm

  • Anechoic saccular lesion along the HA course with a yin yang color pattern and a to and fro spectral waveform
  • Extrahepatic cases arise at the anastomosis; intrahepatic cases follow biopsy or biliary procedures
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Card 15  ·  Transplant: Liver Rejection and Late Findings
Front
SITM
TRANSPLANT
Rejection and Biliary
UltrasoundDilated intrahepatic bile ducts with thickened walls and an anastomotic biliary stent in a liver transplant.
Anastomotic biliary stricture

Rejection

  • Acute rejection appears within the first 10 days with right upper quadrant pain, fever, hepatomegaly, and rising liver function tests
  • Ultrasound findings are nonspecific; an elevated RI or periportal edema may be seen and biopsy is required
  • Chronic rejection deteriorates the graft slowly and drives fibrosis

Biliary complications

  • Occur in 5 to 15 percent of liver transplants, most within the first 3 months
  • Obstruction is the most common, usually an anastomotic stricture; biliary complications as a group are the second most common cause of allograft dysfunction after rejection
  • Intrahepatic strictures are ischemic and follow HA compromise, since the HA is the only blood supply to the ducts

Bile leak

  • Bile leaks occur in about 5 percent, more than 70 percent within the first month, most often at the biliary tube site
  • A perihepatic biloma is a round, hypoechoic or anechoic collection with no vascular flow
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TRANSPLANT
Late Findings
UltrasoundHyperechoic mass in the right hepatic lobe of a transplanted liver, consistent with recurrent hepatocellular carcinoma.
HCC recurrence in the transplanted liver

Fluid collections

  • Hematomas are perihepatic, echogenic when fresh, and liquefy as they age; most resolve without drainage
  • Seromas are round, thin walled, and anechoic and resolve in a few weeks
  • Ultrasound is sensitive for a fluid collection but nonspecific for its contents; CT or MRI differentiates blood, bile, lymph, and serous fluid

HCC recurrence

  • Hepatocellular carcinoma recurs after transplant in about 40 percent of patients
  • The most common site of recurrence is the lung, followed by the liver
  • Hepatitis C reinfection is nearly universal in HCV recipients and drives graft loss through rapid fibrosis

PTLD and gas

  • Posttransplant lymphoproliferative disorder is a hypoechoic soft tissue mass that may encase the hepatic hilum
  • Portal venous gas is common and benign in the early postoperative period, but beyond it points to bowel ischemia with a 75 to 90 percent mortality
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Card 16  ·  Transplant: Renal Normal Doppler
Front
SITM
TRANSPLANT
Normal Values
UltrasoundArcuate artery spectral waveform in a renal transplant with a normal low-resistance pattern and a resistive index in the sixties.
Arcuate artery with normal RI

Renal artery

  • Rapid systolic upstroke with continuous diastolic flow, a low-resistance waveform
  • Peak velocity should stay below 250 cm per second
  • Renal to iliac artery ratio should stay below 3.0

Arcuate RI

  • Normal arcuate resistive index ranges from 0.60 to 0.70
  • Borderline values fall between 0.70 and 0.80
  • Angle correction is not needed for RI, but is required whenever measuring velocity

Veins and iliac

  • Renal vein and iliac vein show continuous monophasic flow with minimal respiratory change
  • Iliac artery and common femoral artery show a triphasic waveform

Reading the RI

  • A low RI can be an indirect sign of a proximal renal artery stenosis that is otherwise hidden
  • A high RI suggests rejection, renal venous congestion, or chronic small vessel disease
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TRANSPLANT
Vascular Complications
UltrasoundRenal artery anastomosis with color aliasing and spectral Doppler showing peak velocities well above 250 cm per second.
Renal artery stenosis at the anastomosis

Artery stenosis

  • One of the most common vascular complications, usually within the first year and at the anastomosis or from atherosclerosis in the donor artery
  • Peak velocity above 250 cm per second and a renal to iliac artery ratio above 3.0 strongly suggest stenosis
  • Tardus parvus arcuate waveforms indicate an upstream lesion
  • Percutaneous transluminal angioplasty with or without a stent succeeds in about 73 percent of patients

Vein thrombosis

  • Rare, in less than 5 percent of transplants, usually within the first postoperative week
  • The kidney appears edematous with venous congestion and no venous flow
  • The arterial waveform shows reversal of diastolic flow, an urgent finding requiring thrombectomy

Rejection and ATN

  • Both cause an enlarged graft with nonspecific RIs between 0.80 and 0.90; biopsy separates them
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Card 17  ·  Transplant: Renal Urologic and Other
Front
SITM
TRANSPLANT
Urinary Tract
UltrasoundModerate hydronephrosis in a transplanted kidney with a dilated distal ureter at the ureteroneocystostomy.
Distal ureteric obstruction in the graft

Urinary obstruction

  • Seen in about 2 percent of renal transplants and almost always within the first 6 months
  • Ureteral stenosis is distal in more than 90 percent, from ischemic scarring, kinking, or surgical technique
  • Balloon dilation succeeds in about 90 percent, and stents are usually removed after 10 days

Leaks and stones

  • Urine leaks and urinomas usually appear within the first 2 weeks; a urinoma is anechoic, well defined, without septations, and grows rapidly
  • About 1 to 2 percent develop significant stones, echogenic foci that shadow or twinkle on color Doppler

Biopsy AVF

  • A biopsy creates an arteriovenous fistula in about 10 percent of renal transplant patients
  • Spectral Doppler shows a high velocity, low-resistance waveform with arterialization of the draining renal vein
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TRANSPLANT
Infection and Neoplasm
UltrasoundHypoechoic soft tissue mass adjacent to the transplant renal hilum with regional lymphadenopathy.
PTLD near the transplant hilum

Infection

  • More than 80 percent of renal transplant recipients develop at least one infection within the first year
  • Emphysematous pyelonephritis contains gas in the collecting system with shadowing or reverberation
  • Debris or low-level echoes in a dilated collecting system with fever suggest pyonephrosis
  • Any peritransplant fluid in a symptomatic patient should be considered infected until proven otherwise

PTLD

  • Posttransplant lymphoproliferative disorder occurs in 1 to 20 percent of all transplants and in about 0.8 percent of renal transplant patients
  • Long-term immunosuppression raises malignancy risk 2 to 5 times above the general population
  • Appears as a hypoechoic soft tissue mass, often near the renal hilum

Autotransplant

  • The patient's own kidney is removed and reimplanted into the iliac fossa for ureteral injury, renovascular disease, or intractable stone disease
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Card 18  ·  Transplant: Pancreas Allograft
Front
SITM
TRANSPLANT
Anatomy and Doppler
IllustrationPancreas transplant in the right iliac fossa with the donor iliac Y graft to the common iliac artery, donor portal vein to the recipient iliac vein confluence, and enteric drainage to the terminal ileum.
Pancreas allograft with the Y graft anastomosis

Surgical anatomy

  • Placed in the right or left lower quadrant, with the right lower quadrant typically preferred
  • Arterial inflow is a donor iliac artery Y graft joining the SMA and splenic artery to the recipient common iliac artery
  • Venous outflow is the donor portal vein to the recipient common iliac vein and IVC confluence
  • Enteric drainage is a side to side anastomosis between the allograft duodenum and the terminal ileum

Combined transplants

  • About 75 percent of pancreas transplants are simultaneous pancreas-kidney; the kidney is placed in the left iliac fossa and the pancreas in the right

Normal Doppler

  • Pancreatic artery peak velocity should stay below 200 cm per second
  • Intraparenchymal artery RI should stay below 0.80
  • Pancreatic duct should measure less than 3 mm
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TRANSPLANT
Complications
UltrasoundEnlarged pancreatic transplant with a heterogeneous echotexture in acute rejection.
Acute pancreatic rejection

Rejection

  • Rejection is the primary cause of allograft loss, occurring in 5 to 25 percent of patients
  • Acute rejection appears 1 to 3 weeks postoperatively with pancreatic enlargement and heterogeneous echotexture
  • Chronic rejection drives fibrosis and atrophy, and the pancreas may not be visible on ultrasound
  • Elevated glucose, amylase, and lipase correlate poorly with severity, so biopsy is required for a diagnosis

Thrombosis

  • Acute thrombosis occurs in 2 to 10 percent of transplants, more often on the venous side than the arterial
  • Venous thrombosis is the second most common cause of allograft failure, usually within the first 6 weeks
  • With venous thrombus, the pancreatic arterial waveform shows reversal of diastolic flow

Other

  • Pancreatitis is the second most common complication overall; mild pancreatitis affects about 35 percent of patients within the first 4 weeks
  • A pseudocyst is anechoic and thin walled, with occasional layering debris and no internal flow
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