Covered metallic stenting for malignant distal biliary obstruction: clinical results according to stent type

Background In the endoscopic management of unresectable malignant biliary obstructions, covered metallic stents (CMSs) showed longer patency and lower incidence of stent occlusion than uncovered metallic stents (UMCs). However, there are very few reports on factors influencing the results of inserting CMSs. We evaluated differences in clinical results according to stent type. Methods We reviewed the results of four types of CMS (polyurethane-covered Diamond stent (PCD), silicone-covered WALLSTENT (SCW), ComVi stent, and VIABIL biliary stent) and an uncovered MS (UMS), based on our experience and the literature. CMSs were characterized according to the axial and radial forces, covering (partial, full), smoothness of the inner surface, and presence of an anti-migration system. Results CMSs were patent significantly longer than UMSs. There were differences in stent patency among the CMSs, including the cause of occlusion and other complications. The PCD had good patency and a low incidence of migration. The ComVi stent occluded early due to food impaction, but had the longest median stent patency and a low migration rate. The incidence of migration of SCW was relatively high and the SCW was occluded primarily by sludge. Conclusions We should assess the differences between the various CMSs and select the best one for each patient.