ERCP is a procedure that enables your doctor to diagnose conditions in the gall bladder and bile ducts. It is commonly used to treat these conditions, remove gall stones and relieve obstruction in the biliary tree.
A long flexible tube, about the thickness of your little finger, is passed through your mouth into the stomach and duodenum, or small intestine. In the duodenum, a small opening is identified, and a plastic tube, or cannula, is passed through the endoscope and into the opening.

Contrast medium, dye, is injected which outlines the biliary and pancreatic ducts and xrays are taken.