Sonographic diagnosis of biliary ascariasis.

In a prospective 6 month study, sonographic diagnosis of biliary ascariasis was made in 12 patients: In five, the diagnosis was confirmed by other means, mainly intravenous cholangiography. In three, such confirmation was not sought, but all had proven intestinal infestation. One possible and three definite false-positive diagnoses were made. There were no established false-negative diagnoses. The echogenic, nonshadowing images of the worms were seen in the main bile duct and/or gallbladder as single strips (on one occasion with its digestive tract seen as an anechoic "inner tube"), as multiple strips giving a spaghettilike appearance, as coils, or as more amorphous fragments. Follow-up sonograms were obtained in six patients and showed expulsion of the worms by medical treatment.