Acute pancreatitis is the most common complication of endoscopic retrograde cholangiopancreatography (ERCP). The incidence of post-ERCP pancreatitis (PEP) is estimated to be 10% to 15% in high-risk patients. Current guidelines recommend using pancreatic duct stent (PDS) for PEP prevention in high-risk patients, but it is not clear whether stent length will affect the effect of PEP prevention. The longer PDS will remain in the pancreatic duct for a longer period of time, thereby ensuring prolonged decompression with subsequent lowering of the risk for PEP. Findings from two retrospective studies showed that longer PDS was more effective in reducing the risk of post-ERCP hyperamylasemia and the frequency of PEP compared with the shorter PDS. We conducted this trial to test whether 7cm PDS was superior to 5cm PDS in PEP prevention in high-risk patients.

Inclusion Criteria:

1. Un-intentional pancreatic duct cannulation:

   • 2 or more times;
   • 1 time with more than 10 minutes cannulation.

2. Double-wire technique;

3. High-risk patients:

met at least 1 of the major criteria

• Clinical suspicion of sphincter of Oddi dysfunction;
• Pancreatic sphincterotomy
• Delayed precut sphincterotomy
• ≥ 8 cannulation attempts
• Pneumatic dilatation of an intact biliary sphincter
• Ampullectomy

or met at least 2 or more of the minor criteria

• Age < 50;
• Female;
• Normal TBIL;
• ≥ 3 injections of contrast into the pancreatic duct with ≥ 1 injection to the tail of the pancreas;

Exclusion Criteria:

• Therapeutic PDS;
• Acute pancreatitis within 3 days;
• With a history of pancreatic surgery or biliary-enteric anastomosis;
• Pregnant or breastfeeding women;
• unwilling or inability to provide consent.