Our aim is to compare the efficacy of 100 mg versus 200 mg rectal indometacin in preventing post-ERCP pancreatitis (PEP) among high-risk patients without no pancreatic stenting. The 100 mg versus 200 mg indometacin trial is a multicentre, single-blind, randomized controlled study. High-risk patients for PEP without pancreatic stent insertion will be informed about the opportunity to participate. A total of 1,036 eligible patients will be randomly assigned in a 1:1 ratio to one of two groups: (1) administration of 100 mg rectal indometacin immediately after ERCP (standard-dose group), or (2) administration of 200 mg rectal indometacin immediately after ERCP (high-dose group). The primary outcome is the incidence and severity of PEP. Secondary outcomes include hyperamylasemia and other ERCP-related adverse events (AEs).

Evidence suggests that escalating the rectal indometacin dose to 200 mg offers no clear advantage over the standard 100 mg regimen in high-risk patients. However, the majority of participants (76%) had received pancreatic stent placement, raising the possibility that the benefit of the supplementary strategy may have been obscured by the considerable efficacy of pancreatic stenting. Our aim is to compare the efficacy of 100 mg versus 200 mg rectal indometacin in preventing post-ERCP pancreatitis (PEP) among high-risk patients without no pancreatic stenting.

Inclusion Criteria:Participants will be eligible for enrollment if they meet all of the following criteria: 1. age over 18 years; 2. classified as high risk for post-ERCP pancreatitis; 3. provision of signed, written informed consent.

Exclusion Criteria:Participants will be excluded if they meet any of the following conditions: 1. inaccessible major papilla; 2. surgically altered gastrointestinal anatomy; 3. current diagnosis of acute pancreatitis; 4. placement of a pancreatic stent; 5. contraindications to nonsteroidal anti-inflammatory drugs (NSAIDs), including known allergy, renal insufficiency, or active peptic ulcer disease; 6. anticipated low risk of post-ERCP pancreatitis (e.g., patients with chronic calcific pancreatitis, pancreatic head mass, or those undergoing biliary interventions through a pre-existing sphincterotomy); 7.severe active cardiopulmonary disease; 8. pregnancy or breastfeeding; 9. presence of an ampullary tumor.

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We are committed to promoting transparency and open science. Upon reasonable request and under certain conditions, individual participant data (IPD) from our study may be shared for further research. Access to the IPD will be considered on a case-by-case basis, following review and approval of a formal proposal by Qiao Mei.

To inquire about accessing the IPD, interested parties may contact Qiao Mei at meiqiaomq@aliyun.com.

Please note that data sharing is contingent upon meeting the criteria for ethical use, privacy, and confidentiality as outlined in our data sharing policy. Additionally, appropriate data transfer agreements may need to be established prior to sharing.

For enhanced objectivity in data analysis, the project statisticians will be blinded to the arm allocation.