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Differential Diagnosis of Echogenic Material within Gallbladder include?

  • Gallstone(s) (mobile, shadowing). 
  • Gallbladder sludge (mobile, non-shadowing).
  • Gallbladder polyp (non-mobile, non-shadowing, often attached to the gallbladder wall via a stalk, and may be vascular).
  • Hyperplastic cholecystoses (non-mobile, multiple polyps).


Risk Factors for Developing Gallstones?

MNEMONIC: The Four "Fs"

Fat, Fertile (preggers), Forty year old Female, who is also diabetic. 


What is the wall-echo-shadow (WES) sign?

A gallbladder completely dilled with stones can be more challenging to identify. The wall-echo-shadow WES sign 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.


What are the characteristic ultrasound findings of acute cholecystitis? 

  • Gallstones are seen >90% of the time
  • + Murphy's sign
  • 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). 


What are the complications of acute cholecystitis?

  • 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 are often present.


Differential Diagnosis of an Echogenic Gallbladder Wall

  • Porcelain gallbladder
  • A Gallbladder packed full of stones (which will feature the wall-echo-shadow sign)
  • Emphysematous cholecystitis (intramural gas will have dirty shadowing).


What is a porcelain gallbladder?

Ultrasound appearance?

  • 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 cholecystectomy is the standard of care.
  • On ultrasound, the wall of the gallbladder is echogenic, and there are almost always associated gallstones.  The gallbladder demonstrates dense shadowing, which could be mistaken for gas in the gallbladder wall (emphysematous cholecystitis) or gallstones in the lumen of the gallbladder. 


What is a 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).


What is hyperplastic cholecystosis?

  • The hyperplastic cholecystoses 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 gallbladder wall adenomyomatosis and strawberry gallbladder to gallbladder polyps extending into the lumen.


What is adenomyomatosis of the gallbladder?

Ultrasound finding?

  • 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 ar fact due to reflections off of tiny crystals seen in a focally thickened and echogenic gallbladder wall.


What is the typical ultrasound appearance of a gallbladder polyp, and what is the main differential consideration?

  • 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.


What are the characteristics of a gallbladder polyp which increases its risk of being malignant?

MNEMONIC: The "Six S's" of a "Sad Gallbladder"

  1. 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.
  2. Single: A solitary polyp is more suspicious for malignancy. In contrast, benign cholesterol polyps tend to be multiple.
  3. Sessile (broad-based): Sessile morphology is suspicious. A polyp is more likely benign if pedunculated.
  4. Stones: The presence of stones may induce chronic in amma on, which can predispose towards malignancy.
  5. Primary Sclerosing cholangitis increases the risk of malignancy.
  6. Sixty (age) or greater.



What are the ultrasound findings of primary gallbladder carcinoma?

  • 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.


What are the risk factors for developing primary gallbladder cancer?

  • 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.

(Pretty much the "Six S's" that make gallbladder polyp riskier, and add porcelain gallbladder and IBD/ulcerative colitis)


Common Ultrasound Imaging Patterns: 

Diffuse Gallbladder Wall Thickening > 3mm

  • 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.
    • Diverticulitis.
  • Infiltrative neoplastic disease
    • Gallbladder carcinoma.
    • Metastases to gallbladder (rare, and if so then melanoma).
  • Post-prandial state.


Common Ultrasound Imaging Patterns: 

Focal Gallbladder Wall Thickening

  • Hyperplastic cholecystoses: 
    • Adenomyomatosis and cholesterol polyp.
  • Vascular: Varices
  • Neoplastic disease:
    • Adenomatous polyp
    • Gallbladder carcinoma
    • Adjacent hepatic tumor


Common Ultrasound Imaging Patterns:

Non-Shadowing "Mass" in the Gallbladder Lumen

  • Tumefactive sludge (mobile).​
  • Blood/pus (mobile).
  • Gallbladder polyp (immobile).
  • Gallbladder carcinoma (immobile).


Common Ultrasound Imaging Patterns:

Echogenic Gallbladder Wall

  • Porcelain gallbladder.
  • Gallbladder full of stones (signified by the wall-echo- shadow sign).
  • Emphysematous cholecystitis.


What is 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 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.


What is pneumobilia?

Contrast this to portal venous gas. 

US findings

  • 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.


What is cholangiocarcinoma?

What is a Klatskin tumor?

  • Cholangiocarcinoma 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 FarEast).
  • 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.


What is the rule of thumb for assessing common bile duct (CBD) dilation?

  • A rule of thumb for assessing the common bile duct diameter CBd is to assume that the CBD ought to be 6 mm or less before age 60, but may still be normal if 1 mm larger per decade after that age (an 8 mm duct in an 80-year-old patient may be considered normal). 
  • The common bile duct is approximately 1.6 mm wider on average in patients who have undergone cholecystectomy, compared to patients who have not had a cholecystectomy.
  • In general, malignancy causes more prominent ductal dilation than benign disease.


US appearance of cholelithiasis

  • The ultrasound diagnosis of gallstones is usually straightforward. Stones are echogenic with posterior acoustic shadowing and 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.