Rectal indomethacin and pancreatic duct (PD) stenting (PDS) are recommended for the prevention of post-ERCP pancreatitis (PEP). However, the effects of the combination of the two methods on preventing PEP are controversial. We hypothesized that some group of patients with difficult cannulation might benefit from the combination of indomethacin plus PDS (IP) compared with indomethacin alone (IN).

Inclusion Criteria:

1. Patients underwent diagnostic or therapeutic ERCP
2. With native papilla
3. With difficult cannulation (cannulation time >10min or cannulation attempts >5 times or inadvertently PD cannulation ≥1)
4. Receiving post-ERCP rectal indomethacin

Exclusion Criteria:

1. Patients with indications of PD cannulation
2. No attempt of cannulation due to inaccessible papilla
3. Non-difficult cannulation

Patients who underwent ERCP and received administration of rectal indomethacin.