Sonography of hepatobiliary ascariasis.

We present the real-time sonographic features of 19 surgically proven cases of hepatobiliary ascariasis, in which ultrasound examination was the primary modality used to achieve the diagnosis. All the patients presented with right upper quadrant abdominal symptoms. There were no false positive diagnoses. The "impacted worm" sign, reported here for the first time, presented in two patients as long curved, tubular, non-shadowing structures with echoluscent cores, in the distribution of the intrahepatic biliary ducts. Both of these patients died soon after surgery indicating poor prognosis in such cases. Two other patients are described in whom macerated round worms were seen as intraluminal, localized, soft tissue masses in the common duct mimicking a cholangiocarcinoma. Thus, biliary ascariasis must be added to the differential diagnosis of an intraluminal bile duct mass in patients from endemic areas.