Predictive factors for the necessity of peroral cholangioscopy-guided lithotripsy in the endoscopic treatment of cystic duct confluence stones: a retrospective study in Japan

BACKGROUND: The treatment of cystic duct confluence stones often requires peroral cholangioscopy (POCS)-guided lithotripsy. This study evaluated the efficacy of endoscopic treatment for cystic duct confluence stones and identified predictive factors for the need for POCS-guided lithotripsy. METHODS: This retrospective cohort study included 38 patients with cystic duct confluence stones treated endoscopically between September 2007 and December 2023. The primary outcome was the rate of complete stone removal. Secondary outcomes included the number of sessions, total procedure time, adverse events, and predictive factors for POCS-guided lithotripsy. RESULTS: The complete stone removal rate was 100%. POCS-guided lithotripsy was required in 50% of the cases. The mean number of sessions needed for stone removal was 2.05. The mean procedure time was 93.9 minutes. The incidence of adverse events was 13%. Multivariate analysis showed that a minor axis length of the stone relative to the distal bile duct diameter greater than 1.2 was an independent predictive factor for requiring POCS-guided lithotripsy. CONCLUSIONS: Endoscopic treatment is highly effective for cystic duct confluence stones. However, POCS-guided lithotripsy was necessary when the minor axis of the stone relative to the distal bile duct diameter exceeded 1.2.