Safety, efficacy, and removability of a fully covered multi-hole metal stent in a swine model of hilar biliary stricture: a feasibility study

Background and study aims Use of fully covered self-expandable metal stents (FCSEMS) for biliary drainage of malignant hilar biliary strictures is limited because of risk of cholangitis due to side branch obstruction. The aim of this study was to evaluate the safety and efficacy of unilateral placement of a multi-hole FCSEMS (FCSEMS-MH), which had a 2.5-mm hole in the center of the membrane on each cavity, in a swine model of hilar biliary stricture. Materials and methods Six female mini pigs were included in this prospective study. The hilar biliary stricture model was prepared using an endobiliary radiofrequency ablation. FCSEMS-MHs were endoscopically inserted into the peri-hilar bile duct of all the animals. Outcomes were assessed in terms of adverse events (AEs) including cholangitis, stent patency, stent migration, and endoscopic stent removability for 1 month after stenting. Results In terms of hilar biliary stricture types, two animals were of Bismuth type I and four were of type II. Technical success rate for endoscopic metal stenting was 100 % (6/6), and the functional success rate, which was evaluated 7 days after stent insertion, was also 100 % (5/5). The immediate overall AE rate was 0 %. There was no procedure-related mortality and stent migration did not occur in any animal during the 4-week stent indwelling period. Stents were removed from all six animals at 4 weeks post-stenting. Conclusion Unilateral placement of FCSEMS-MH might be safe and effect for swine hilar biliary stricture models. However, long-term follow-up and comparative studies are needed to verify the usefulness of this stent.