This study is a randomized clinical trial evaluating the efficacy of rectal indomethacin in preventing post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis in patients undergoing biliary ERCP who have a history of prior biliary sphincterotomy. While rectal indomethacin has demonstrated benefits in preventing post-ERCP pancreatitis in high-risk patients, its utility in this specific patient subgroup remains unclear. This trial aims to determine whether prophylactic administration of indomethacin offers a measurable benefit over no intervention in this lower-risk population.

Eligible patients will be identified prior to their scheduled biliary ERCP and screened for inclusion criteria. Following informed consent, participants will be randomized to receive either rectal indomethacin or no indomethacin prior to the procedure.

Inclusion Criteria:

1. Male or female ≥ 18 years of age at the time of ERCP.
2. Scheduled to undergo routine biliary ERCP with documentation of a prior biliary sphincterotomy.
3. Ability to receive rectal medication.
4. Ability and willingness to comply with all study procedures and follow-up requirements.
5. Written informed consent (and assent when applicable) was obtained from the subject or the subject's legal representative, and the subject's ability to comply with the requirements of the study was confirmed.

Exclusion Criteria:

1. Pregnant, breastfeeding, or unwilling to practice birth control during participation in the study.
2. Known hypersensitivity or contraindication to indomethacin, other nonsteroidal anti-inflammatory drugs, or suppository components.
3. Active gastrointestinal bleeding, history of NSAID-induced gastrointestinal ulceration, or other conditions that contraindicate NSAID use.
4. Significant renal impairment (e.g., baseline serum creatinine above institutional upper limit of normal or estimated glomerular filtration rate < 30 mL/min/1.73 m²).
5. Current use of other NSAIDs that cannot be safely discontinued per the investigator's judgment.
6. Known chronic pancreatitis
7. Presence of a condition or abnormality that, in the opinion of the Investigator, would compromise the safety of the patient or the quality of the data.