All of the following can cause obstruction of hepatobiliary system EXCEPT (AIIMS Nov 2012)
a. Infestation of the biliary tract by adult helminths or their ova may produce a chronic, recurrent pyogenic cholangitis with or without multiple hepatic abscesses, ductal stones, or biliary obstruction. This condition is relatively rare but does occur in inhabitants of southern China and elsewhere in Southeast Asia.
b. The organisms most commonly involved are trematodes or flukes, including Clonorchis sinensis, Opisthorchis viverrini or O. felineus, and Fasciola hepatica.
c. The biliary tract also may be involved by intraductal migration of adult Ascaris lumbricoides from the duodenum or by intrabiliary rupture of hydatid cysts of the liver produced by Echinococcus spp.
d. The diagnosis is made by cholangiography and the presence of characteristic ova on stool examination.
e. When obstruction is present, the treatment of choice is laparotomy under antibiotic coverage, with common duct exploration and a biliary drainage procedure.