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.
The 57 printed cards
Eleven topics in the order of your list: vascular system, liver, gallbladder and biliary, spleen, pancreas, gastrointestinal tract, peritoneal cavity and abdominal wall, urinary system, retroperitoneum, thyroid and parathyroid, scrotum. Every topic carries the same depth, weighted to how much the reference text gives it, so liver and urinary run longest and the peritoneal cavity runs shortest.
Card 1 · Vascular System: Aorta & IVC
Front
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)
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
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
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
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
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
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.
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
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
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
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
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.
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).
IllustrationFatty (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
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
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
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
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
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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
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
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
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
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
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
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.
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
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
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.
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
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
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
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
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
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
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
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
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
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
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.
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.
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
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
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
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
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
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.
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
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.
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
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, weighted to how much the reference text gives each one. 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
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
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
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.
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.
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
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.
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
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
Card 15 · Transplant: Liver Rejection and Late Findings
Front
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
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
