Removal of Duckbill-type laser-cut anti-reflux metal stents: Clinical evaluation and in vitro study.

Objectives: Duckbill-type metal stent (DMS) was the first laser-cut biliary metal stent with an anti-reflux valve. Removal of DMS is believed to be difficult and relevant reports are scarce. This study aims to investigate the feasibility of DMS removal. Methods: We retrospectively analyzed patients who underwent DMS removal between June 2019 and March 2022 to evaluate success rates and factors affecting outcomes. In addition, six different methods of DMS removal were reproduced in vitro, varying removal devices, angle of applied force, and grasped location. Extraction resistance, the distance of forceps stroke, and stent length after removal were compared. Results: Forty patients were enrolled, and DMS removal was successful in 31 cases (78%). No adverse events were observed. Tumor ingrowth was evident in 78% (7/9) of failed cases. Patients receiving biliary metal stents for the first time (naïve cases), long indwelling time, longer stent, and stent tearing during removal were associated with unsuccessful stent removal. In the in vitro study, a larger force was required to remove the stent at an extraction angle of 120° than at 0°. Among cases in which force was applied at 120°, the load tended to be lower when rat-tooth forceps were applied horizontally across the stent. Conclusions: Stent removal was possible in a majority of cases. Deployment of additional stents inside DMS may be preferable to forceful removal in the presence of factors associated with difficult stent removals, such as tumor ingrowth, naïve cases, longer stents, long indwelling time, and stent tearing during removal.

Endoscopic Transluminal Stent Placement for Malignant Afferent Loop Obstruction.

BACKGROUND: Malignant afferent loop obstruction (ALO) is rare condition and is difficult to manage. Endoscopic transluminal treatment has become easier with the advent of balloon-assisted enteroscopes with a large working channels and self-expandable metal stent (SEMS) with a 9 Fr delivery system. METHODS: From July 2016 to March 2022, 22 patients with symptomatic malignant ALO who underwent endoscopic transluminal treatment (Initial cohort), of which 18 patients received endoscopic transluminal SEMS placement (SEMS cohort), were retrospectively evaluated. We evaluated outcomes of endoscopic transluminal treatment and long-term outcomes of SEMS placement for malignant ALO. RESULTS: In the Initial cohort, technical and clinical success rates were both 95.5%. The median procedural time was 28.0 min. One case of guidewire-induced micro-perforation occurred as an early complication (4.5%). In the SEMS cohort, and no early complication was observed. Recurrent obstruction occurred in two cases (11.1%) during the follow-up period (median: 102 days). One was managed by additional SEMS placement and the other was treated conservatively. CONCLUSIONS: High technical and clinical success was achieved by endoscopic transluminal treatment with short procedural time for malignant ALO. Endoscopic SEMS placement also appears to be safe and effective, and additional SEMS placement can be considered in cases of re-obstruction.