Acoustic artifacts and reverberation shadows in gallbladder sonograms: their cause and clinical implications

From among more than 7000 sonographic examinations of the gallbladder performed over a period of 2 years, different types of acoustic artifacts were observed in 42 patients. Artifacts originated in the gallbladder wall in 37 cases and within the lumen in 5 cases. Eighteen patients had symptoms related to the hepatobiliary area. Twenty-four patients were fully asymptomatic although cholelithiasis was demonstrated in 8. In 21 cases (50%) some type of gallbladder pathology was associated with the presence of acoustic artifacts. Thirteen patients were cholecystectomized and the associated gallbladder pathology consisted of cholelithiasis (N = 5), cholesterolosis (N = 2), adenomyomatosis (N = 2), emphysematous cholecystitis (N = 2), and acute cholecystitis (N = 2). In 3 of these patients a sonographic/pathologic correlation was established. Only 5 of the 18 symptomatic patients presented acoustic artifacts in an otherwise normal gallbladder. Recognition of those pathological conditions favorable to the appearance of artifacts and reverberation shadows is extremely useful for differentiating merely clinically irrelevant anomalies from those that require prompt management.