Sonographic appearances in biliary ascariasis

Biliary ascariasis is as frequent a cause of adult biliary disease as gallstones in Kashmir Valley, India. In the present study, we prospectively evaluated the role of sonography in the diagnosis of biliary ascariasis and its utility in monitoring the exit of worms from the bile duct. Sonography was performed on 28 patients with biliary ascariasis proven by endoscopic retrograde cholangiopancreatography. The bile ducts were dilated on sonography in 26 patients. The characteristic sonographic features of worms in the bile duct were as follows: (a) a single, long, linear or curved echogenic structure without acoustic shadowing (2 patients); (b) multiple, long, linear, parallel echogenic strips, usually without acoustic shadowing (15 patients); (c) a thick, long, linear or curved, nonshadowing echogenic strip containing a central, longitudinal anechoic tube, probably representing the digestive tract of the worm (7 patients); and (d) characteristic movement of these long echogenic structures within the bile duct (8 patients). One patient with pancreatic ascariasis exhibited long, linear, nonshadowing echogenic strips in a dilated pancreatic duct. Other sonographic changes observed in these patients were (a) gallbladder distention (10 patients), edema of the gallbladder wall (8 patients), sludge within the gallbladder (11 patients), a coiled echogenic structure within the gallbladder (1 patient); (b) multiple liver abscesses (1 patient); and (c) edematous pancreatitis (4 patients). Sonography detected worms in the biliary tree in 24 of 28 patients (85.7%). Serial sonograms accurately demonstrated the spontaneous exit of worms in 18 patients and the persistence of worms in 3 patients. Sonography is a simple, rapid, and noninvasive method for diagnosis and follow-up of patients with biliary ascariasis.