Ultrasound Flashcards
Cholelithiasis
Cholelithiasis is the presence of a gallbladder stone or stones, without associated inflammation.
The classic clinical presentation of symptomatic cholelithiasis is colicky pain after eating a fatty meal, but it is common to see gallstones incidentally in asymptomatic patients.
Risk factors for developing gallstones include female sex, obesity, pregnancy, middle age, and diabetes.
The ultrasound diagnosis of gallstones is usually straightforward. Stones are echogenic with posterior acoustic shadowing are are often mobile. It is often helpful to reposition the patient (typically in the left lateral decubitus position) while scanning to assess whether the stones layer dependently to differentiate stones from polyps or other masses.
A gallbladder completely filled with stones can be more challenging to identify. The wall-echo-shadow (WES) signn describes the appearance of a gallbladder full of multiple stones (or one giant stone).
Two parallel echogenic arcs represent the gallbladder wall and leading edge of the stone, with an intervening thin layer of hypoechoic bile. The gallstone typically casts a prominent shadow.
The differential diagnosis of echogenic material within the gallbladder includes:
Gallstones (mobile shadowing)
Gallbladder sludge (mobile, non-shadowing)
Gallbladder polyp (non-mobile, non-shadowing, often attached to the gallbladder wall via a stalk, may be vascular).
Hyperplastic cholecytoses (non-mobile, multiple polyps).
Acute calculous cholecystitis
Acute cholecystitis is inflammation of the gallbladder, usually due to a gallstone impacting the cystic duct. Ultrasound is the first-line evaluation of suspected acute cholecystitis.
Acute cholecystitsi clinicaly presents with right upper quadrant (RUQ) pain and fever.
There is no 100% specific ultrasound finding for acute cholecystitis. However, gallstones are seen >90% of the time and a postivie sonographic Murphy’s sign (RUQ pain with pressure from the transducer) also has a high positive predictive value. Other findings include: Gallbladder wall thickening >3 mm. Distended gallbladder >4 cm in diameter. Pericholecystic fluid. Color Doppler showing hyperemic gallbladder wall. Hyperechoic fat in the gallbladder fossa (ultrasound correlate to CT finding of fat stranding).
Complications of acute cholecystitis are rare but serious. Emphysematous cholecystitis is gas in the gallbladder wall and has a high risk of gallbladder perforation. Gangrenous cholecystitis is necrosis of the gallbladder wall. Sonographic findings include layering echogenic material in the gallbladder lumen representing hemorrhage and sloughed membranes. Gallbladder perforation appears as focal discontinuity of the gallbladder wall. Perihepatic ascites containing dirty echoes is often present.
Surgical treatment of uncomplicated acute calculous cholecystitis is cholecystectomy. In patients who are not good surgical candidates, a temporizing percutaneous cholecystostomy tube can be placed prior to definitive surgical cholecystectomy.
Acalculous cholecystitis
Acalculous cholecystitis is cholecystitis without gallstones, typically seen in very sick patients. Risk factors include sepsis, prolonged total parenteral nutrtion, and trauma.
The ultrasound appearance is similar to acute cholecystitis but without stones. Since many patients are ventilated or obtunded, it’s often not possible to evaluate for sonographic Murphy’s sign.
Treatment of acalculous cholecystitis is typically interventional radiology percutaneous cholecystostomy. Unlike the treatment of calculous cholecystitis, cholecystostomy is often the definitive therapy.
Emphysematous cholecystitis
Emphysematous cholecystitis is a rapidly progressive form of acute cholecystitis characterized by gas in the gallbladder wall. Emphysematous cholecystitis is associated with gallbladder ischemia causing bacterial translocation. Treatment is urgent surgery.
On ultrasound, gas is usually present in both the gallbladder lumen and wall, which appears as echogenic lines and foci with posterior dirty shadowing.
Porcelain gallbladder
A porcelain gallbladder is a calcified gallbladder wall due to either chronic irritation from supersaturated bile or repeated bouts of gallbladder obstruction.
Porcelain gallbladder is associated with an increased risk of gallbladder cancer, but the incidence is controversial. In general, prophylactic choleycystectomy is the standard of care.
On ultrasound, the wall of the gallbladder is echogenic, and there are almost always associated gallstones.
The differential diagnosis of an echogenic gallbladder wall includes a porcelain gallbladder, a gallbladder packed full of stones (which will feature the wall-echo-shadow sign), or emphysematous choleycystitis (intramural gas will have dirty shadowing).
Courvoisier gallbladder
The Courvoisier gallbladder refers to a markedly dilated gallbladder (originally described as being so large as to be directly palpable) from malignant obstruction of the common bile duct.
A markedly distended gallbladder implies chronic obstruction of either the cystic duct (when seen in isolation) or the common bile duct (when seen in combination with dilation of the common bile duct and intrahepatic biliary dilation).
Overview of hyperplastic cholecytoses
The hyperplastic cholecytoses are a spectrum of non-neoplastic proliferative disorders caused by deposition of cholesterol-laden macrophages within the wall of the gallbladder. The cholecystoses range from abnormalities of the gallbladdr wall (adenomyomatosis and strawberry gallbladder) to gallbladder polyps extending into the lumen.
Adenomyomatosis
Adenomyomatosis is cholesterol deposition in mural Rokitansky-Aschoff sinuses. It is important not to confuse with adenomyosis of the uterus: It may be helpful to remember that there are three L’s in gallbladder, and adenomyomatosis is a longer word than adenomyosis.
The ultrasound hallmark of adenomyomatosis is the comet-tail artifact due to reflections off of tiny crystals seen in a focally thickened and echogenic gallbladder wall.
Strawberry gallbladder (cholesterolosis of the gallbladder)
Strawberry gallbladder is a pathologic diagnosis that is not apparent by imaging. It is characterized by tiny mural cholesterol depsosits likened to strawberry seeds.
Gallbladder polyps
Most gallbladder polyps are benign cholesterol polyps that are part of the hyperplastic cholecytosis spectrum. Rarely (<5%), polyps may be premalignant adenomas.
Clinically, gallbladder polyps may cause right upper quadrant pain or even cholecystitis if the cystic duct is obstructed.
The following characteristics, known as the six S’s, increase the risk for a polyp being malignant: Size >10 mm or rapid growth. As a caveat, ultrasound has limited sensitivity and specificity in detecting small polyps (<10 mm), especially in the presence of gallstones. Single: A solitary polyp is more suspicious for malignancy. In contrast, benign cholesterol polyps tend to be multiple. Sessile (broad-based): Sessile morphology is suspicious. A polyp is more likely benign if pedunculated. Stones: The presence of stones may induce chronic inflammation, which can predispose towards malignancy. Primary Sclerosing cholangitis increases risk of malignancy. Sixty (age) or greater.
In patients with several of these high-risk features, cholecystectomy should be considered in the presence of a polyp greater than 6 mm in size.
The typical ultrasound appearance of a polyp is a non-mobile, non-shadowing polypoid lesion extending from the wall into the lumen of the gallbladder. There may be vascular flow in the stalk.
The main differential consideration is adherent sludge, which will not have any vascular flow.

Primary gallbladder carcinoma
Gallbladder cancer is a rare malignancy with a poor prognosis. A typical clinical presentation may include right upper quadrant pain, weight loss, and jaundice.
Risk factors for development of gallbladder cancer include: Gallstones and chronic cholecystitis. Porcelain gallbladder (somewhat controversial). Primary sclerosing cholangitis. Inflammatory bowel disease (ulcerative colitis more frequently than Crohn disease). Adenomatous polyp >10 mm or >6 mm with multiple risk factors, as described above.
Ultrasound shows a polypoid mass with increased vascularity in the gallbladder. There is often direct invasion into the liver. Regional adenopathy occurs early. Bile duct obstruction may be present.
Gallbladder metastases
Metastases to the gallbladder are uncommon.
Hepatocellular carcinoma can spread directly to the gallbladder through the bile ducts.
Melanoma can spread hematogenously to the gallbladder mucosa.
Diffuse gallbladder wall thickening >3 mm (most common causes)
Fluid-overload/edematous states: Cirrhosis - Hypoalbuminemia leads to diffuse gallbladder wall thickening. Congestive heart failure. Protein-wasting nephropathy.
Inflammatory/infectious: Cholecystitis, usually with associated cholelithiasis. Hepatitis. Pancreatitis. Diverticultitis.
Infiltrative neoplastic disease: Gallbladder carcinoma. Metastases to gallbladder (rare).
Post-prandial state.
Focal Gallbladder wall thickening (common causes)
Hyperplastic cholecystoses: Adenomyomatosis and cholesterol polyp.
Vascular: Varices.
Neoplastic disease: Adenomatous polyp. Gallbladder carcinoma. Adjacent hepatic tumor.
Non-shadowing “mass” in the gallbladder lumen
Tumefactive sludge (mobile).
Blood/pus (mobile).
Gallbladder polyp (immobile).
Gallbladder carcinoma (immobile).
Echogenic gallbladder wall
Porcelain gallbladder
Gallbladder full of stones (signified by the wall-echo-shadow sign).
Emphysematous cholecystitis.
Choledocholithiasis
Choledocholithiasis is a stone in the common bile duct, generally treated with ERCP.
Mirizzi syndrome
Mirizzi syndrome is seen when a stone in the cystic duct causes inflammation and external compression of the adjacent common hepatic duct (CHD).
Essential for the surgeon to know about preoperatively because the CHD may be mistakenly ligated instead of the cystic duct. Additionally, inflammation can cause the gallstone to erode into the CHD and cause a cysto-choledochal fistula and biliary obstruction.
On ultrasound, a stone is typically impacted in the distal cystic duct, and the CHD is dilated. The cystic duct tends to run in parallel with the CHD.
Pneumobilia
Pneumobilia is air in the biliary tree. It is commonly seen after biliary interventions, but may be due to cholecystoenteric fistula or rarely emphysematous cholecystitis.
On ultrasound, small echogenic gas bubbles are seen centrally in the liver with posterior dirty shadowing.
In contrast to pneumobilia, portal venous gas (which implies bowel ischemia until proven otherwise) is peripheral and causes a spiky appearance of the portal vein spectral Doppler waveform.
Cholangiocarcinoma
Cholangiocarcinom is cancer of the bile ducts. It classically presents with painless jaundice. Most cases of cholangiocarcinoma are sporadic, although key risk factors include chronic biliary disease (in the US) and liver fluke infection (in the Far East).
The hilum is the most common location of cholangiocarcinoma. A hilar cholangiocarcinoma is known as a Klatskin tumor. Intrahepatic cholangiocarcinoma occurs uncommonly (10%).
Ultrasound plays a role in the initial evaluation of adjacent adenopathy and vascular structures. Local nodes include porta hepatis and hepatoduodenal ligament nodes. If more distal nodal disease is present, then the tumor is generally considered unresectable.
Hepatic Steatosis
Hepatic steatosis is the accumulation of excess fat within hepatocytes due to a metabolic derangement (obesity or diabetes), hepatotoxins (EtOH), or prolonged fasting.
Ultrasound shows a diffuse increase in hepatic echogenicity. Normally, the liver and kidney should have the same echogenicity. With fatty infiltration, the liver appears more echogenic than the kidney. Hepatic steatosis also causes increased sound attenuation, leading to poor visualization of deeper structures.
Focal fat sparing is a geographic area of hypoechogenicity in an otherwise fatty liver. A characteristic location of focal fat sparring is the gallbladder fossa.
Cirrhosis
Cirrhosis is the replacement of functioning hepatocytes with dysfunctional fibrotic tissue, due to long-standing repeated cycles of hepatocyte injury and repair.
Micronodular cirrhosis causes cirrhotic nodules less than 3 mm in size and is most commonly associated with alcoholism.
Macronodular cirrhosis features larger nodules (>3 mm) separated by wide scars and fibrous septae. Macronodular cirrhosis is caused by fulminant viral hepatitis which does not uniformly affect the liver.
The typical utrasound appearance of cirrhosis is a coarse, heterogeneously increased liver echotexture with a nodular external contour. In early cirrhosis, the superficial nodularity is best appreciated with a high frequency linear probe. The caudate lobe is often spared and hypertrophies in response to increased demand (the caudate has direct venous drainage into the IVC and therefore can bypass the hypertensive portal system). End-stage cirrhosis is characterized by a shrunken, nodular liver.
Signs of portal hypertension are often present, including an enlarged portal veins, splenomegaly, varices, portosystemic shunts, and a patent umbilical vein. Imaging of portal hypertension is discussed in detail in the liver Doppler section.
Viral hepatitis
Viral hepatitis is infection of the liver by a hepatotropic virus. Hepatitis B and C cause chronic disease.
The most common ultrasound finding is a normal liver. Occasionally periportal edema produces the characteristic starry sky pattern of increased portal triad echogenicity.
Acute hepatitis is often associated with diffuse severe gallbladder wall thickening.
Pyogenic abscess
Pyogenic abscess is caused by pus-forming organisms and is usually due to spread from intestinal or biliary infection (most commonly E. coli)
Infection starts as an ill-defined area of altered echogenicity (phlegmon stage) that evolves into a well-defined hypoechoic structure with internal echoes (mature abscess).






