PLASTIC STENT PLACEMENT ABOVE THE SPHINCTER OF ODDI (“INSIDE STENT”) FOR BILIARY STRICTURES

Abstract

Although endoscopic plastic stent placement is useful and safe for biliary strictures, the high stent occlusion rate and short stent patency remain important problems. Stent occlusion is caused by food impaction and sludge formation due to the reflux of duodenal contents into the bile duct. The inside stent, which is stent placement above the intact sphincter of Oddi, has been invented to retain the function of the sphincter of Oddi and to prevent the reflux of duodenal contents. In Japan, inside stents are employed for biliary strictures after living-donor liver transplantation and malignant biliary strictures, and favorable outcomes have been obtained. Although the design of the inside stent needs to be improved to reduce the risk of migration and to facilitate stent removal, the inside stent is expected to decrease the risk of ascending infection and to prolong the duration of stent patency. However, the development of more simplified, safer and dedicated devices is indispensable so that inside stents may become widespread. Moreover, a randomized, controlled trial of the inside stent compared with conventional stent placement is mandatory to evaluate the efficacy and safety of inside stents.