I, myself, had pain on and off for quite a long time several years after gallbladder surgery. My gastro dr. ordered an MRCP which essentially is an MRI of the pancreas and biliary ductwork. This test is not invasive nor is it dangerous. The ERCP, however, which is a definitive test to treat problems of the bile and biliary ducts pancreas, entails introducting a catheter into the ductwork itself using a contrast dye for imaging under fluoroscopy to look for narrowed areas or blockages which also allows for biopsies, stone removal, tumor removal, etc. This latter procedure can end up possibly causing perforations and infections, and possible excessive bleeding. Notabl, it can also cause pancreatitis which can be life threatening. From what I have read, not all regular gastro drs. do ERCPs since they appear to realize how dangerous they may be if not performed properly.