Sonographic evaluation of biliary ascariasis.

In a prospective 6-month study, sonographic diagnosis of biliary ascariasis was made in 14 patients; in nine patients, the diagnosis was confirmed by endoscopic retrograde cholangiopancreatography and bile analysis, while in five patients, confirmation was obtained by proven intestinal infestation. No false-positive or false-negative cases were encountered. Ascariasis of the biliary tract was seen on ultrasound as echogenic, non-shadowing images, either as single or multiple strips, with visualization of the digestive tract of the worm as an anechoic inner tube, or as amorphous fragments. Follow-up sonograms helped in detection of worm expulsion following medical therapy in five patients, while endoscopic extraction of the worm was performed in four patients. In three patients, disappearance of the worm from the biliary tract was noted following a therapeutic sphincterotomy, and two patients detected to have a worm within the gall-bladder were operated on. In all patients, serial sonograms revealed disappearance of the worm, and the regression of biliary tract dilatation.