The non-visualized gallbladder by ultrasonography implications and differential diagnosis.

The findings in 42 consecutive patients in whom the gallbladder or its lumen were not visualized ultrasonographically were reviewed retrospectively for evidence of gallbladder disease. The series contains two groups of patients--the larger comprised 32 patients in whom the gallbladder was represented only by a dense echogenic focus, with acoustic shadowing, in the right upper quadrant, thought to be due to cholelithiasis in a small contracted gallbladder. The accuracy of this finding in predicting gallbladder disease was 96%. The smaller group consisted of eight patients in whom the gallbladder was not visualized. In seven patients with follow-up, the accuracy of this finding in predicting gallbladder disease was only 71%. Dense echoes in the right upper quadrant were not always due to cholelithiasis but to emphysematous cholecystitis in one patient, porcelain gallbladder in a second, and agenesis of the gallbladder in a third.