Prophylactic PS Placement to Prevent Pancreatitis After Endoscopic Transpapillary GPC for Cholelithiasis With Concomitant Choledocholithiasis

Inclusion Criteria: 1. Patients aged 18 years or older; 2. Patients with gallbladder stones and common bile duct (CBD) stones confirmed by ultrasound and/or MRCP or other imaging modalities (CT/MRI); 3. Patients with every gallbladder stone ≤1 cm in diameter or sludge-like stones; 4. Patients without a history of gastrointestinal reconstruction surgery,cholecystectomy or previous biliary surgery, includes ERCP; 5. The morphology and size of the gallbladder are essentially normal and the thickness of the gallbladder wall is ≤3 mm; 6. Patients with at least one of the following high-risk factors for post-ERCP pancreatitis (PEP): suspected sphincter of Oddi dysfunction (SOD), female sex, history of pancreatitis, difficult cannulation (defined as ≥5 cannulation attempts or ≥5 minutes of cannulation time), pancreatic duct contrast injection, age \<35 years, non-dilated extrahepatic bile duct, no history of chronic pancreatitis, normal serum bilirubin, precut sphincterotomy, biliary balloon dilation, incomplete bile duct stone clearance, or intraductal ultrasound ; 7. Patients who voluntarily provide signed informed consent. Exclusion Criteria: 1. Patients with any of the following diagnoses: chronic atrophic cholecystitis, porcelain gallbladder, suspected gallbladder malignancy, or Mirizzi syndrome; 2. Patients with ectopic duodenal papilla or congenital pancreaticobiliary malformations; 3. Patients unfit for ERCP endoscopic treatment due to severe systemic diseases; 4. Patients with severe coagulation dysfunction (defined as an International Normalized Ratio \[INR\] \>1.5) or significant thrombocytopenia (platelet count \<50×10⁹/L); 5. Pregnant women; 6. Patients with guidewire entry into the pancreatic duct ≥3 times during the procedure; 7. Patients with allergies to aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs); 8. Patients with congenital or acquired absence of the rectum; 9. Patients with severe acute pancreatitis