Impact of Sphincterotomy on Suprapapillary Inside Stent Patency in Unresectable Malignant Hilar Biliary Obstruction: A Multicenter Cohort Study.

Background and Study Aims The role of endoscopic sphincterotomy (EST) during suprapapillary inside stent placement for unresectable malignant hilar biliary obstruction (MHBO) remains uncertain. We evaluated its association with stent patency and adverse events. Patients and Methods This multicenter retrospective cohort included 376 consecutive patients treated at 8 institutions (2014-2024). The primary outcome was time to recurrent biliary obstruction (TRBO). Multivariable Cox regression, 1:1 propensity score matching (PSM), and competing-risk analysis were performed. Patients with prior EST were excluded from index-procedure safety analyses. Results Clinical success was achieved in 315 patients; 244 (77.5%) were in the EST group. TRBO did not differ between the EST and non-EST groups overall (median 170 vs 157 days; p = 0.85), after PSM (196 vs 207 days; p = 0.49), or in adjusted Cox analysis (hazard ratio 1.21, 95% CI 0.77-1.90). Competing-risk analysis likewise showed no difference (Gray's p = 0.45). Among 360 patients without prior EST, PEP occurred in 7.8% versus 11.0% ( p = 0.388), PEB in 1.5% versus 0% ( p = 0.576), and perforation in 0.4% versus 0% ( p = 1.000) in the index EST and non-EST groups, respectively. The single perforation was type III and was classified as mild in severity. Conclusions EST was not associated with longer initial stent patency. These retrospective findings do not support routine EST solely to prolong patency; its potential role in facilitating subsequent transpapillary reinterventions requires prospective evaluation.