Pitfalls and differential diagnosis in biliary sonography.

Ultrasonography has a primary role in the imaging of biliary disease. Most cases are straightforward, but the authors emphasize unusual manifestations, uncommon diseases, and artifacts that may present diagnostic challenges. Issues in differential diagnosis are discussed for the following findings: internal gallbladder echoes (calculi vs tumefactive sludge, air, hematobilia, parasitic infestation, cholecystosis, neoplasia, and artifacts), gallbladder wall thickening (acute cholecystitis vs acalculous cholecystitis, artifacts, ascites, hypoalbuminemia, hepatitis, and sclerosing cholangitis), pericholecystic fluid (cholecystitis vs ascites, perforated ulcer, and trauma), bile duct dilatation (biliary obstruction vs sclerosing cholangitis, biliary air, anomalous portal system, biliary atresia, Caroli disease, and cholangiocarcinoma), perinatal and neonatal biliary disease, and sclerosing cholangitis.