The goal of this clinical trial is to learn about Efficacy of the ETGBD parallel insertion with fully covered self-expandable metal stent for preventing acute cholecystitis in patients with low cystic duct insertion.

In this study, we hypothesized that endoscopic transpapillary gallbladder drainage (ETGBD) with parallel insertion of a fully covered self-expanding metal stent(FCSEMS) through an endoscopic biliary drainage tunnel is superior in preventing complications such as cholecystitis when the gallbladder ducts confluence within the distal third of the common bile duct. And we aimed to confirm its efficacy by comparing the frequency, severity, and rate of invasive additional procedures due to cholecystitis complications to provide evidence of clinical utility.

Inclusion Criteria:

1. Adults 19 years of age or older
2. Patients requiring endoscopic retrograde cholangiography and drainage for therapeutic purposes.
3. Patients with imaging (CT, Cholangiogram) confirmed confluence of the cystic duct with the distal third of the common bile duct.
4. Patients who have voluntary informed consent to participate in the study.

Exclusion Criteria:

• Patients who have undergone percutaneous/surgical bile duct or gallbladder drainage prior to study enrollment.
• Patients with anatomic deformity of the upper gastrointestinal tract after gastric or hepatobiliary surgery
• Patients with concomitant gastric/duodenal obstruction
• Patients with confirmed or suspected cystic duct obstruction on imaging studies
• Patients with acute cholecystitis, acute pancreatitis
• Patients who underwent cholecystectomy
• Patients with a life expectancy of less than 3 months
• Patients who are otherwise unable to undergo endoscopic retrograde cholangiopancreatography