The stomach leads to the first part of the small intestine, also called the duodenum. The common bile duct carries bile from the liver to the duodenum, and enters the duodenum a few centimeters beyond the stomach.
Gallstones usually form in the gallbladder. Gallstones sometimes pass from the gallbladder into the common bile duct, and block the flow of bile into the duodenum. This can result in serious illness. Additionally, tumors of the pancreas and duodenum can block the bile duct, also preventing the flow of bile into the duodenum.
Procedure, part 1
ERCP is a technique in which an endoscope, with a camera on its end, is passed down the esophagus, through the stomach, and into the duodenum. The entrance of the common bile duct into the duodenum can be viewed through the endoscope. Next, the surgeon can pass a special instrument on the end of the endoscope into the common bile duct as it enters the duodenum. Dye is injected through this instrument into the common bile duct; this allows for the visualization of gallstones by X-ray.
Procedure, part 2
If gallstones are present in the common bile duct, the surgeon can perfom a sphincterotomy. A small incision is made through the endoscope, which enlarges the opening of the common bile duct into the duodenum. The stones can then pass through.
Procedure, part 3
If a tumor is present and constricting the bile duct, a plastic or metal stent can be placed into the bile duct, thus holding it open, and allowing bile to pass through.