This study is designed to learn whether rinsing the papilla with cold water at the end of an ERCP procedure, in addition to standard medicine, can help lower the chance of developing pancreatitis, which is the most common major complication after ERCP.

Study design:

This is an investigator-initiated, single-center, triple-blind, parallel-group, randomized controlled superiority trial. Participants will be randomized 1:1 to receive either (1) rectal indomethacin plus cold water irrigation or (2) rectal indomethacin plus room-temperature water irrigation. The study is designed to evaluate whether cold water irrigation provides additive benefit in reducing the incidence of post-ERCP pancreatitis (PEP) compared with standard therapy.

Eligible patients (≥20 years, native papilla) undergoing ERCP at University of Kansas Medical Center (KUMC) will be identified during pre-procedure evaluation. Written informed consent will be obtained prior to the procedure.

Baseline Data Collection: Demographic data, relevant medical history, ERCP indication, and risk factors for PEP will be recorded before the procedure.

All patients receive a 100 mg rectal indomethacin suppository at the completion of ERCP.

Participants are randomized to receive either 250 mL of cold water (experimental arm) or room-temperature water (control arm) directed toward the papilla in five 50 mL aliquots, with aspiration between each injection.

Monitoring During ERCP: Continuous monitoring of heart rate, non-invasive blood pressure, oxygen saturation, and sedation status will be performed throughout the procedure per standard of care.

Post-Procedure Monitoring: Patients will be monitored in the recovery unit and inpatient setting as clinically indicated. Laboratory tests (amylase, lipase, Complete Blood Count (CBC), metabolic panel) will be obtained if patients develop post-procedure abdominal pain or clinical suspicion of pancreatitis.

Risk Minimization, Drugs/Devices, and Source Records :

• Risk Minimization: All patients receive guideline-recommended NSAID prophylaxis (indomethacin).Cold water irrigation volume and temperature are standardized to avoid mucosal injury or systemic effects. Experienced endoscopists will perform all procedures. Patients will be closely monitored during and after ERCP for early recognition of adverse events.

• Drugs/Devices: Rectal indomethacin (100 mg suppository) - FDA-approved NSAID, used off-label for PEP prevention.

Sterile water for irrigation (cold or room temperature) - procedural adjunct, not investigational.

• Source Records: Electronic medical record (Epic) for demographics, labs, and hospital course. Procedure reports and nursing documentation. Case report forms (CRFs) and study data collection sheets maintained in a secure REDCap database.

Inclusion Criteria:

• Native papilla present.
• Undergoing ERCP for diagnostic or therapeutic indications.
• Able to provide informed consent.

Exclusion Criteria:

• Post-operative reconstructed intestinal tract other than Billroth I reconstruction.
• Acute pancreatitis at the time of ERCP.
• Chronic pancreatitis.
• Pancreatic head cancer with occlusion of the main pancreatic duct.
• Existing pancreatic duct stent or need for prophylactic pancreatic duct stenting during the index ERCP.
• Known contraindications or allergy to indomethacin or other NSAIDs.
• Significant renal impairment (eGFR < 30 mL/min/1.73m²).
• Active peptic ulcer disease or history of NSAID-induced gastrointestinal bleeding.

All personnel involved in this project are the University of Kansas (KU)-affiliated physicians/researchers; therefore, there are no anticipated issues regarding the sharing of individual participant data (IPD).