Post-endoscopic retrograde cholangiopancreatography(ERCP) pancreatitis (PEP)remains the most frequent adverse event of ERCP. Rectal indomethacin, as one kind of classic NSAIDs, has been proved to be effective in reducing the incidence of PEP. It has been widely used to prevent PEP in patients, especially those with potentially high risks of PEP. However, rectal indomethacin can not completely eradicate the occurrence of PEP. The rate of PEP in patients receiving indomethacin ranges from 3.2% to 9.2%. The risk factors of PEP in patients receiving rectal indomethacin remains unclear. The aim of the study was to identify potential risk factors in high-risk patients whose received administration of prophylactic rectal indomethacin after ERCP.