Gallbladder ascariasis with uneventful worm migration back to the duodenum: A case report.

Ascariasis, a worldwide parasitic disease, is regarded by some authorities as the most common parasitic infection in humans. The causative organism is Ascaris lumbricoides, which normally lives in the lumen of the small intestine. From the intestine, the worm can invade the bile duct or pancreatic duct, but invasion into the gallbladder is quite rare because of the anatomical features of the cystic duct, which is narrow and tortuous. Once it enters the gallbladder, it is exceedingly rare for the worm to migrate back to the intestine. We report a case of gallbladder ascariasis with worm migration back into the intestine, in view of its rare presentation.