Rectal Indomethacin to Prevent Post-ERCP Pancreatitis

Inclusion Criteria: * Patients undergoing diagnostic or therapeutic ERCP. Exclusion Criteria: * Unwillingness or inability to consent for the study; * Age \< 18 years old; * Intrauterine pregnancy; * Breastfeeding mother; * Standard contraindications to ERCP; * Allergy to NSAIDs; * Received NSAIDs in prior 7 days; * Renal failure (Cr \>1.4mg/dl=120umol/l); * Active or recurrent (within 4 weeks) gastrointestinal hemorrhage; * Acute pancreatitis within 72 hours; * Known pancreatic head mass; * Subject with prior biliary sphincterotomy now scheduled for repeat biliary therapy without anticipated pancreatogram; * ERCP for biliary stent removal or exchange without anticipated pancreatogram; * Known active cardiovascular or cerebrovascular disease. * Presence of coagulopathy before the procedure or received anticoagulation therapy within three days before the procedure;