Gallbladder Stenting in FC-SEMS

The goal of this randomized controlled trial is to determine whether primary prophylaxis with transpapillary gallbladder drainage prevents acute cholecystitis after fully-covered self-expandable metal stents placement during endoscopic retrograde cholangiopancreatography for malignant distal biliary obstruction in patients at higher risk of post-endoscopic retrograde cholangiopancreatography acute cholecystitis. The main question it aims to answer is: Does prophylactic transpapillary gallbladder drainage reduce the rate of post-endoscopic retrograde cholangiopancreatography acute cholecystitis in high-risk patients? Researchers will compare patients who undergo transpapillary gallbladder drainage to patients without transpapillary gallbladder drainage to see if transpapillary gallbladder drainage reduces the rate of acute cholecystitis. Participants will: 1. receive or not transpapillary gallbladder drainage before fully-covered self-expandable metal stents placement 2. will be followed up at one, three, and six months to ascertain the onset of acute cholecystitis