Fig. 10.24 Ultrasound scans of Ascaris in the bile ducts. (A) Seen as a lone echogenic linear structure in the dilated common bile duct (CBD) of a 27-year-old Egyptian man with icterus, fever, hepatomegaly, splenomegaly, and an eosinophilia of 50%. (Courtesy of Dr. Y. Zaki, Alexandria, Egypt.) (B) Another roundworm in the common bile duct of a different patient. (C and D) Ascaris worms in the right (C) and left (D) hepatic ducts of two different South African patients. (Courtesy of Dr. A. Shulman, Tygerberg Hospital, and Dr. S. Mandel, Capetown.)

Fig. 10.25 (A) A lone Ascaris (arrow) can be identified in the pancreatic duct of a South African patient.(B) Following treatment, the worm is no longer present in the duct (arrows). (Courtesy of Dr. A. Shulman, Tygerberg Hospital, and Dr. S. Mandel, Capetown).

Ultrasonography is easily the procedure of choice for recognizing the presence of Ascaris in the hepatobiliary tract, pancreatic duct, and gallbladder (Figs. 10.24 and 10.25), because of its widespread availability in the tropics, its relatively low cost, and its high diagnostic accuracy in the hands of trained personnel. In a 1987 study from India, Khuroo et al prospectively evaluated the role of sonography in the diagnosis of biliary ascariasis and its utility in monitoring the exit of worms from the bile ducts. They noted that ascariasis was as frequent a cause of adult biliary disease as gallstones in Kashmir.

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 ducts were as follows (Fig. 10.24): (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 (Fig. 10.25).

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), and 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. They, as well as numerous other investigators, have concluded that sonography is a simple, rapid, and noninvasive method for diagnosis and follow-up of patients with biliary ascariasis.