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OBJECTIVES Colorectal stenting is widely performed using self-expandable metallic stents (SEMSs), but the mechanical properties have not been evaluated. Therefore, we conducted an in vitro study to evaluate the mechanical properties of colorectal SEMSs. METHODS Eighteen individual types and sizes of uncovered SEMSs were evaluated for their mechanical properties. Radial force was measured using a measurement machine. Axial force (AF) was measured by two methods: a conventional manual method and a new method using a measurement machine. The correlation of these two methods was evaluated. We also proposed an "AF zero border" that was defined as the angle at which the torque force disappeared. RESULTS Radial force versus diameter curves and AF versus angle curves were influenced by the structure and the size of each stent. There was excellent correlation of AFs measured by the new and conventional manual method (y = 21.434x, R = 0.881, P

Background and Aim To evaluate the efficacy and safety of secondary gastroduodenal stent placement after first stent dysfunction for malignant gastric outlet obstruction. Methods We conducted a retrospective analysis to investigate the efficacy and safety of secondary stent-in-stent gastroduodenal stent placement. Results Among 260 patients who had been treated with first gastroduodenal stent placement for malignant gastric outlet obstruction, 29 patients (11.2%) were treated with secondary gastroduodenal stent placement because of first stent dysfunction. Pancreatic cancer was the major primary cancer (55.2%). A WallFlex duodenal stent was the most frequently inserted stent both as a first stent (75.9%) and as a secondary stent (62.1%). There were 22 patients (75.9%) that received gastroduodenal stents at the bending site (supraduodenal angle or infraduodenal angle). Technical and clinical success rates were 100% and 86.2%, respectively. Median eating period was 3.0 months, and median survival time was 3.5 months. As for related complications, gastrointestinal perforation, insufficient stent expansion, tumor ingrowth, tumor overgrowth, and cholangitis were experienced in 13.8% (four cases), 6.9% (two cases), 6.9% (two cases), 3.4% (one case), and 3.4% (one case), respectively. Conclusion Secondary gastroduodenal stent placement might be effective for managing first stent dysfunction in malignant gastric outlet obstruction. However, gastrointestinal perforation was the major complication.

Background Self-expandable metallic stent (SEMS) placement is widely carried out for distal malignant biliary obstruction, and survival analysis is used to evaluate the cumulative incidences of SEMS dysfunction (e.g. the Kaplan–Meier [KM] method and the log–rank test). However, these statistical methods might be inappropriate in the presence of ‘competing risks’ (here, death without SEMS dysfunction), which affects the probability of experiencing the event of interest (SEMS dysfunction); that is, SEMS dysfunction can no longer be observed after death. A competing risk analysis has rarely been done in studies on SEMS. Patients and Methods We introduced the concept of a competing risk analysis and illustrated its impact on the evaluation of SEMS outcomes using hypothetical and actual data. Our illustrative study included 476 consecutive patients who underwent SEMS placement for unresectable distal malignant biliary obstruction. Results A significant difference between cumulative incidences of SEMS dysfunction in male and female patients via theKM method (P = 0.044 by the log–rank test) disappeared after applying a competing risk analysis (P = 0.115 by Gray's test). In contrast, although cumulative incidences of SEMS dysfunction via the KM method were similar with and without chemotherapy (P = 0.647 by the log–rank test), cumulative incidence of SEMS dysfunction in the non-chemotherapy group was shown to be significantly lower (P = 0.031 by Gray's test) in a competing risk analysis. Conclusion Death as a competing risk event needs to be appropriately considered in estimating a cumulative incidence of SEMS dysfunction, otherwise analytical results may be biased.

Background Feasibility of antireflux metal stent (ARMS), designed to prevent duodenobiliary reflux, was reported in patients with distal malignant biliary obstruction. In this prospective pilot study, we aimed to evaluate a newly designed ARMS as a reintervention for self-expandable metallic stent (SEMS) occlusion believed to be caused by duodenobiliary reflux. Patients and Methods Patients with non-resectable distal malignant biliary obstruction were included in whom a prior SEMS was occluded as a result of sludge or food impaction between March 2010 and January 2012 at two Japanese tertiary referral centers. The occluded SEMS were endoscopically removed, if possible, and subsequently replaced by a newly designed ARMS. We evaluated the technical success rate and complications of ARMS and compared the time to occlusion of ARMS with that of prior SEMS. Results A total of 13 patients were included. ARMS was successfully placed in all patients in a single procedure. No procedure-related complications were identified. ARMS occlusion occurred in two patients (15%), the causes of which were sludge in one patient and unknown in the other. ARMS migration occurred in four patients (31%). ARMS patency time was significantly longer than that of prior SEMS (median, not available vs 58 days; P = 0.039). Conclusions This newly designed ARMS is a technically feasible, safe, and effective reintervention for SEMS occlusion as a result of sludge or food impaction. An anti-migration mechanism to improve the outcomes of ARMS should be considered.

Aim Stent migration due to peristalsis of the colon is one of the unresolved complications of colonic self-expandable metallic stent (SEMS) placement. Axial force (AF), a recovery force of the stent to a straight position after bending, has been considered a factor influencing the conformability of the digestive tract. An uncovered SEMS (Niti-S Enteral Colonic Uncovered Stent, D-type; Taewoong, Inc., Gimpo, South Korea) with improved conformability is considered to decrease migration. Methods Thirty three consecutive patients with symptomatic colorectal obstruction between March 2006 and December 2011 underwent endoscopic stent placement for palliation to estimate the efficacy and safety of Niti-S stents prospectively in four tertiary referral centers. Results Technical and clinical success rates were 100% and 97%, respectively. Seventeen patients had the following complications: ingrowth (n = 6), overgrowth (n = 1), collapse of the SEMS (n = 1), stool impaction (n = 2), migration (n = 1), bleeding (n = 3), and tenesmus (n = 3). The patient with migration had no recurrent symptoms until death. Of these 17 patients, 10 required re-interventions. Seven patients underwent an additional SEMS implantation. One patient underwent surgery for stoma creation. Two patients had stool impaction, and they underwent endoscopic cleaning. The median duration of patency was 347.0 ± 65.5 days. The mean survival time after stent insertion was 240.1 ± 39.9 days. Conclusion The new SEMS effectively relieves malignant colorectal obstruction. Good conformability, according to the very low AF, may contribute to the low incidence of migration.

Aim This retrospective study estimated the efficacy and safety of the WallFlex duodenal stent for malignant gastric outlet obstruction (GOO) in Japan. Methods Forty-two consecutive patients with symptomatic malignant GOO were treated using WallFlex duodenal stents between January 2010 and October 2010. Results The technical and clinical success rates were 100% and 83.3%, respectively.The median gastric outlet obstruction scoring system increased significantly, from 0 to 2, after stent placement (P

Aim: As for self-expandable metallic stents (SEMS) for malignant gastric outlet obstruction (GOO), some predictive factors of stent patency have been reported, although re-canalization of GOO by SEMS does not necessarily lead to favorable food intake. Therefore, we analyzed the predictive factors of oral food intake following SEMS placement. Methods: A total of 97 consecutive patients in whom SEMS were placed for malignant GOO in five hospitals were included in this retrospective study. Clinical outcomes and predictive factors influencing solid food intake were analyzed. Results: The technical and clinical success rates were 97.9% and 87.6%, respectively. The mean gastric outlet obstruction scoring system (GOOSS) improved from 0.39 to 2.24 after SEMS placement (P

Background: The efficacy of double-balloon enteroscopy (DBE) for biliary interventions has been shown in patients with surgical anatomy. However, the use of available endoscopic retrograde cholangiography accessories during this procedure is limited because of the length of the conventional instrument (200 cm). The aim of this study was to evaluate the feasibility of short DBE for managing biliary disorders in patients with a Roux-en-Y gastrectomy or hepaticojejunostomy (HJ). Patients and Methods: Using a short enteroscope (152 cm) and commercially available endoscopic retrograde cholangiography accessories, biliary interventions were performed in six patients with Roux-en-Y reconstruction or HJ anastomosis. Results: A total of 12 biliary interventions were performed; balloon dilations of the HJ anastomosis or intrahepatic ducts (four patients), nasobiliary drainages (three patients), bile duct stone removal after endoscopic papillary large balloon dilation with or without small sphincterotomy (two patients), and a biliary stent placement (one patient). One patient showed retroperitoneal air following endoscopic papillary large balloon dilation, but recovered conservatively. Conclusions: Biliary interventions via DBE using a short enteroscope are feasible in patients with surgical anatomy.

Endoscopic placement of a plastic stent is the standard drainage for a symptomatic benign biliary stricture. Although a removable fully covered self-expandable metal stent has been applied for distal benign biliary stricture, placement of a plastic stent remains the standard treatment for proximal benign biliary stricture. Placement of a plastic stent above the papilla (inside stent) is an alternative to the conventional method because of its preventive effect against the dysfunction of the stent in patients with proximal benign biliary stricture.

Our patient was a 70-year-old man with hepatocellular carcinoma (HCC) and liver cirrhosis (Child-Pugh B). He had a history of distal gastrectomy with Billroth II reconstruction for duodenal ulcer and hepatectomy for HCC. One month after percutaneous radiofrequency ablation (RFA) for recurrent HCC, biliocutaneous fistula was observed. The cholangiogram demonstrated leakage of contrast material from an intrahepatic duct into the fistula, and a nasobiliary catheter was placed. Subsequently, the discharge of bile steadily decreased and stopped. Follow-up cholangiogram revealed no evidence of bile leakage. Biliocutaneous fistula is an extremely rare complication after percutaneous RFA, and the present case report suggests that endoscopic drainage is the first-line therapy for bile leaks after RFA.