Background and study aims We designed a new 7-Fr plastic stent for treating self-expandable metal stent (SEMS) obstruction in patients with malignant hilar biliary obstruction (MHBO) via endoscopic re-intervention with the stent-in-stent (SIS) method and evaluated its efficacy. Patients and methods A total of 33 consecutive patients who underwent endoscopic re-intervention for metal stent obstruction after multi-branched SEMS placement were enrolled. The initial SEMSs were placed in two or three biliary branches in 14 and 19 patients, respectively. We retrospectively evaluated the technical and clinical success, and adverse events. Technical success was defined as successful plastic stent placement into all target branches through the lumen of the SEMS. Results The technical success rates were 85.7 % (12/14) and 78.9 % (15/19) in patients who underwent two- or three-branched biliary drainage, respectively. The clinical success rate was 100 % in the 27 patients in whom technical success was achieved. We achieved successful plastic stent placement in more than two branches, using the new plastic stent combined with a conventional plastic stent, in 97.0 % (32/33). Conclusions This new plastic stent was technically feasible for treating stent obstruction via re-intervention with SIS methods.

The prognostic factors associated with severe-to-fatal post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) remain unclear despite the extensive number of studies on PEP. In total, 3739 ERCP patients with biliary disease with an intact papilla and indicated for ERCP were prospectively enrolled at 36 centers from April 2017 to March 2018. Those with acute pancreatitis diagnosed before ERCP, altered gastrointestinal anatomy, and an American Society of Anesthesiologists (ASA) physical status > 4 were excluded. Univariate and multivariate logistic regression analyses were performed on patient-related factors, operator-related factors, procedure-related factors, and preventive measures to identify potential prognostic factors for severe-to-fatal PEP. Multivariate analyses revealed pancreatic guidewire-assisted biliary cannulation (OR 13.59, 95% CI 4.21–43.83, p < 0.001), post-ERCP non-steroidal anti-inflammatory drug (NSAID) administration (OR 11.54, 95% CI 3.83–34.81, p < 0.001), and previous pancreatitis (OR 6.94, 95% CI 1.45–33.33, p = 0.015) as significant risk factors for severe-to-fatal PEP. Preventive measures included endoscopic biliary sphincterotomy (EST; OR 0.29, 95% CI, 0.11–0.79, p = 0.015) and prophylactic pancreatic stents (PPSs; OR 0.11, 95% CI, 0.01–0.87, p = 0.036). In biliary ERCP, pancreatic guidewire-assisted biliary cannulation, NSAID administration after ERCP, and previous pancreatitis were risk factors for severe-to-fatal PEP, whereas EST and PPS were significant preventive measures for severe-to-fatal PEP.