The safety and efficacy of a new large-bore, fully covered metal stent for the management of unresectable malignant biliary obstruction

[Background] Fully covered self-expandable metallic stents (FCSEMS) are used to drain unresectable distal malignant biliary obstruction. This retrospective study aimed to evaluate the safety and efficacy of a newly developed large-bore FCSEMS. [Methods] We retrospectively analyzed 44 patients with unresectable distal malignant biliary obstruction who received either a 12-mm (n=11) or 10-mm FCSEMS (n=33) between November 2022 and January 2025 at our institution. The primary endpoint was the rate of recurrent biliary obstructions (RBO) during the follow-up period. Secondary endpoints included the causes of RBO and the incidence and causes of complications other than RBO. [Results] The median observation period for the 12-mm and 10-mm groups was 45 days(range:15-561) vs. 81 days (range:10-772), respectively. There was no significant difference in the RBO rate between the groups:2(18.2%) vs. 4(12.1%) (p=0.63). The causes of RBO were kinking and reflux cholangitis in the 12-mm group, whereas in the 10-mm group, the causes included sludge(n=2), food impaction(n=1), and tumor ingrowth(n=1). Complications included pancreatitis(n=2) and cholecystitis(n=1) in the 12-mm group and pancreatitis(n=3) in the 10-mm group. Notably, no cases of stent migration were observed in either group. [Conclusion] The large-bore FCSEMS appears to be a safe and effective option for patients with unresectable distal malignant biliary obstruction, with no observed stent migration.