Comparative Effectiveness Between Indomethacin and Pancreatic Stenting in the Prevention of Post ERCP Pancreatitis

Inclusion Criteria: presence of one of the following risk factors for Post ERCP Pancreatitis 1. sphincter of Oddi dysfunction 2. history of PEP, pancreatic instrumentation or sphincterotomy, precut sphincterotomy, 3. difficult cannulation defined by \>5 cannulation attempts 4. the use of double wire technique in bile duct access 5. at least 2 of the followings including i) female age\<50 ii) 3 pancreatograms iii) acinarization (contrast injection to tail fo pancreas). iv） normal bilirubin； v）guidewire to the tail of pancreas or secondary branches. Exclusion Criteria: * patients intended for pancreatic stenting e.g. those with pancreatic duct strictures, ampullectomy, * without informed consents from patient or next of kin * age \<18 * pregnant or lactating women * patients with altered anatomy except except Billroth I and II gastrectomy * contraindications to the use of NSAIDs such as those with active gastrointestinal bleeding, renal failure (serum creatinine \> 140) * known NSAID allergy * incipient heart failure.