Agenesis of the gallbladder. A cause of false-positive ultrasonography.

Ultrasonography has evolved into a nonhazardous relatively inexpensive means of diagnosing biliary tract disease. It is considered to have a 95 per cent sensitivity for the diagnosis of cholelithiasis. Occasionally, a small contracted gallbladder associated with stones and chronic cholecystitis will be difficult to visualize with ultrasonography. Two patients with agenesis of the gallbladder were recently treated by the authors. Each patient had ultrasonographic evidence suggestive of a contracted gallbladder with stones. Both patients were explored and found to have absent gallbladders and normal operative cholangiograms. Agenesis of the gallbladder is a rare congenital anomaly with a reported incidence of from 0.01 to 0.04 per cent. Approximately 220 cases have been reported in the literature. Most of these are from necropsy studies. Many of these were newborns with more serious anomalies. One might project an increase in adult cases on the basis of increased usage of ultrasonography in patients with abdominal problems. At the present time, only operative findings including cholangiography can be considered as diagnostic of gallbladder agenesis. However, as more of these cases are reported, preoperative awareness of this entity will be increased.