Four-Step Classification of Endoscopic Transpapillary Gallbladder Drainage and the Practical Efficacy of Cholangioscopic Assistance

Background/Aims: Although endoscopic transpapillary gallbladder drainage (ETGBD) has been reported as an alternative procedure for acute cholecystitis, it requires advanced endoscopic techniques. In terms of the certainty of achieving drainage, it remains a challenging procedure. The aim of the current study was to elucidate the practical efficacy of cholangioscopic assistance and to develop a new classification that could be used to evaluate the technical difficulty of ETGBD and provide a theoretical strategy to apply cholangioscopy appropriately for difficult ETGBD. Methods: A total of 101 patients undergoing ETGBD were retrospectively studied. The characteristics and technical outcomes of ETGBD with conventional ETGBD (C-ETGBD) and Spy- Glass DS-assisted ETGBD (SG-ETGBD) were evaluated. The characteristics and technique-dependent factors of unsuccessful C-ETGBD/SG-ETGBD were evaluated using the classification based on the steps of the procedure. The predictive factors of successful C-ETGBD/SG-ETGBD were examined. Results: C-ETGBD was successful in 73 patients (72.3%). SG-ETGBD was successful in 11 of 13 patients (84.6%) who had C-ETGBD failure. Optional SG-ETGBD significantly increased the final success rate (94.1%) compared to C-ETGBD alone (p=0.003). ETGBD procedures could be classified into four steps. SG-assistance worked as an excellent troubleshooter in step 1 (failure to identify the cystic duct orifice) and step 2 (failure of guidewire advancement across the downturned angle of cystic duct takeoff). Magnetic resonance cholangiopancreatography could provide predictive information based on the classification. Conclusions: Optional SG-ETGBD achieved a significantly higher success rate than C-ETGBD alone. Step classification is helpful for determining the technical difficulty of ETGBD and developing a theoretical strategy to apply cholangioscopy in a coordinated manner. (Gut Liver 2021;15:476-485)