Endoscopic retrograde cholangiopancreatography (en-do-SKAH-pik RET-ro-grade ko-LAN-jee-o-PAN-kree-a-TAW-gra-fee). A procedure to x-ray the pancreatic duct, hepatic duct, common bile duct, duodenal papilla, and gallbladder. In this procedure, a thin, lighted tube (endoscope) is passed through the mouth and down into the first part of the small intestine (duodenum). A smaller tube (catheter) is then inserted through the endoscope into the bile and pancreatic ducts. A dye is injected through the catheter into the ducts, and an x-ray is taken.