Evaluation of endoscopic reintervention for self-expandable metallic stent obstruction after stent-in-stent placement for malignant hilar biliary obstruction

Background Bilateral self-expandable metallic stent (SEMS) placement is effective for long-term management of unresectable malignant hilar biliary obstruction (UMHBO). However, endoscopic reintervention (ERI) for bilateral SEMSs is not well-studied. This study aimed to evaluate ERI efficacy after stent-in-stent placement. Methods Data of 31 patients who underwent ERI from May 2000 to July 2018 were analyzed. Results The technical success rate was 80.7% (25/31) and no adverse events occurred. The functional success rate was 100% (25/25). In a multivariate logistic regression analysis, the angle between the bilateral SEMSs (ABBS) >104 degrees (odds ratio 50.49, 95% CI 3.370-2131, P = 0.0039) and overgrowth (odds ratio 25.70, 95% CI 1.121-1234, P = 0.0423) were risk factors for ERI failure. Multiple liver metastases, which sometimes cause overgrowth, were also risk factors. After ERI, some patients underwent additional SEMS (n = 4), plastic stent (n = 14) placement, or internal cleaning of the initial SEMS alone (n = 7). There were no significant intergroup differences in the 50% time to recurrent biliary obstruction. Conclusions ABBS >104 degrees and overgrowth were risk factors for ERI failure after stent-in-stent placement. In the decision-making process for initial SEMS placement for UMHBO, patient condition should be considered, including the angle between bilateral bile ducts and multiple liver metastases.