Sonography of gallstones and biliary dilatation without a visible aetiology: the infrequency of obstructing choledocholithiasis.

This paper describes 50 consecutive patients who sonographically had gallbladder stones and dilated bile ducts, but no visible aetiology for the dilatation. We reviewed these cases to determine the frequency of choledocholithiasis in this setting. Common duct stones caused obstruction in only 36% of these patients. Other aetiologies included strictures due to chronic pancreatitis or prior stone passage in 24% of the patients, and malignant obstruction in 16%. In 24% of the patients, no cause was found for biliary dilatation; common duct stones or obstructing tumours were excluded in the group. Since aetiologies other than stones are likely in a majority of cases, further preoperative workup (CT, percutaneous transhepatic cholangiography, ERCP) or intraoperative cholangiography (if the patient requires urgent cholecystectomy) is indicated. The additional studies should provide a diagnosis, help determine whether or not the common duct should be explored, or avoid unnecessary operation in case of incurable malignancy.