For the procedure, you will lie on your left side on an examining table in an x-ray room. You will be given medication to help numb the back of your throat and a sedative to help you relax during the exam. You will swallow the endoscope, and the physician will then guide the scope through your esophagus, stomach, and duodenum until it reaches the spot where the ducts of the biliary tree and pancreas open into the duodenum. At this time, you will be turned to lie flat on your stomach, and the physician will pass a small plastic tube through the scope. Through the tube, the physician will inject a dye into the ducts to make them show up clearly on x rays. X rays are taken as soon as the dye is injected.
If the exam shows a gallstone or narrowing of the ducts, the physician can insert instruments into the scope to remove or relieve the obstruction. Also, tissue samples (biopsy) can be taken for further testing.