ERCP (Endoscopic Retrograde Cholangiopancreatography) is a technique used to study the ducts (drainage routes) of the gall bladder, pancreas and liver (bile ducts). ERCP is performed with a duodenoscope; along, thin, flexible tube-like instrument. A duodenoscope is passed through the mouth, oesophagus and stomach into the duodenum (the first part of the small intestine). The duodenoscope enables the common opening to the bile and pancreas ducts to be visually identified. A catheter (narrow plastic tube) is passed through the internal channel of the duodenoscope to inject x-ray contrast (dye) into the bile and pancreatic ducts. X-rays enable the doctor to see the images of the ducts and to photograph them.