The Sphincter of Oddi is the muscle complex at the end of the bile and pancreatic duct as it enters through the ampulla of Vater into the duodenum (upper small intestine). Scar tissue with narrowing and/or spasm can be responsible for pain. When patients have attacks of pain, the liver chemistry and pancreatic enzymes may be elevated because of the effects of obstruction. The disease can be documented by measuring the sphincter pressures during an ERCP. After this, making an internal incision of the muscle or sphincterotomy can be accomplished during the same procedure.