The procedure takes place at a hospital, surgery center or clinic. You usually are told to fast for about 8 hours beforehand, and you should avoid smoking and taking certain medications. You might be given antibiotic medication before the procedure to prevent infection. You may also receive a sedative.
Your throat is numbed with a local anesthetic, and then a thin, flexible tube (endoscope) is inserted into your mouth, down your throat and esophagus and into your stomach, small intestine and bile duct. The tube is equipped with a tiny camera that transmits pictures that your doctor sees on a monitor. A small tube is placed in a bile duct near the sphincter of Oddi to measure how it is contracting and expanding. If a problem is found, such as a stone causing a blockage, your doctor might be able to treat it right then.