Incision into a bile duct or any of the canals or passageways that conduct bile.

There are three canals or ducts: the hepatic duct drains bile from the liver; and the cystic duct is an extension of the gallbladder and conveys bile out of that organ.

These two ducts may be thought of as branches that drain into the third duct, the common bile duct, a kind of "trunk", which passes through the wall of the small intestine at the duodenum and joins with the pancreatic duct to form the hepatopancreatic ampulla (cavity in the major duodenal papilla or small elevations [major and minor] on the mucosa of the duodenum into which the common bile duct and the pancreatic duct open).