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.