This is a prospective, multicenter, open-label, randomized controlled trial designed to evaluate the efficacy and safety of prophylactic endoscopic sphincterotomy (ES) in frail patients unfit for cholecystectomy following an episode of acute biliary pancreatitis (ABP).

Eligible patients will be randomized in a 1:1 ratio to either prophylactic ES during the index admission or conservative treatment. The primary endpoint is the time from randomization to the first occurrence of a recurrent pancreatobiliary event within 12 months, including recurrent ABP, cholangitis, choledocholithiasis requiring endoscopic retrograde cholangiopancreatography (ERCP), or cholangiogenic liver abscess. Secondary outcomes include mortality, pancreatobiliary events requiring intensive care unit admission, post-ERCP complications, cholecystitis, and length of hospitalization.

A total of 92 patients will be enrolled. The trial will be led by the Institute of Pancreatic Diseases, Semmelweis University, Budapest, Hungary, and conducted in accordance with Good Clinical Practice.

Inclusion Criteria:

1. adult patients (above 18 years)

2. naïve papilla

3. evidence of AP based on the Atlanta criteria:

   • pain in the upper abdomen
   • serum amylase or lipase concentration > 3 times the upper limit of normal
   • imaging features of acute pancreatitis on abdominal imaging

4. high probability of a biliary etiology:

   • gallstones or biliary sludge on imaging (any type)
   • dilated common bile duct on imaging defined as > 8 mm in patients ≤ 75 years or > 10 mm in patients > 75 years
   • abnormal liver enzymes (alanine aminotransferase [ALT] two times the upper limit of normal)

5. patients unfit for surgery due to the attending physician's decision e.g. American Society of Anesthesiologists (ASA) class ≥ III; severe heart failure with reduced ejection fraction <40%, severe uncontrolled hypertension, chronic kidney disease stage four or five

Exclusion Criteria:

1. previous cholecystectomy

2. previous endoscopic sphincterotomy or pancreatobiliary stenting

3. ERCP/ES is recommended by the guidelines (3)

   • sign of cholangitis
   • presence of CBD stone on any imaging
   • signs of stone in endoscopic ultrasonography or magnetic resonance imaging in case of abnormal liver enzymes (persistently elevated ALT and aspartate aminotransferase (AST) with less than a 20% decrease over four days) or dilated CBD (defined as above)

4. chronic pancreatitis

5. estimated life expectancy < 12 months

6. ERCP is contraindicated, e.g. the procedure cannot be carried out safely due to the patient's comorbidities or physical status; high risk of bleeding or contraindication of the discontinuation of the anticoagulation therapy.

7. ERCP is technically not feasible due to altered anatomy, e.g., total gastrectomy, Roux-en-Y gastric bypass anatomy

8. pancreatobiliary malignancy

De-identified individual participant data (IPD) will be available upon reasonable request to the study investigators after publication.

It will be available from 6 months after publication of the primary results and will remain available for at least 5 years thereafter.

Researchers with a methodologically sound proposal may request access to the de-identified IPD. Requests should be submitted to the corresponding author. Data will be shared after approval of the request and signing a data-sharing agreement, through secure institutional data transfer.