Endoscopic retrograde cholangiopancreatography, or ERCP, is a procedure to diagnose and treat problems in the liver, gallbladder, bile ducts, and pancreas. It combines X-ray and the use of an endoscope—a long, flexible, lighted tube. Your healthcare provider guides the scope through your mouth and throat, then down the esophagus, stomach, and the first part of the small intestine (duodenum). Your healthcare provider can view the inside of these organs and check for problems. Next, he or she will pass a tube through the scope and inject a dye. This highlights the organs on X-ray.