Endoscopic retrograde cholangiopancreatography.

Abstract

A large international multicenter randomized trial was conducted to compare standard polyethylene biliary stents with side holes with new double-layer stents [1]. The theoretical advantages of the new stent design are the absence of side holes (suspected to facilitate bile deposition and thus obstruction) and an inner layer specifically designed to reduce clogging. The outer layer integrates generous flaps, useful for preventing stent migration, and not formed by creating a hole in the inner layer. A total of 110 patients with jaundice due to a malignant stricture of the middle or distal third of the common bile duct were randomly assigned to receive one or other stent type. The stents were 10 Fr in diameter and 5 - 7 cm in length. Twenty of 55 double-layer stents vs. 35 of 55 standard stents became clogged after a mean delay of 144 days (range 48 - 235 days) vs. 97 days (range 13 - 238 days; not statistically significant). A statistically (and clinically) significant difference was observed in stent obstruction at 3 months: 4 % for the double-layer stent vs. 20 % for the standard one. One can speculate that the greater cost of the new stents may, in the future, be shown to be offset by the reduced need for repeat procedures. The hypothesis that side holes are responsible for increased obstruction is not confirmed by a study comparing plastic stents with and without side holes. The results suggest that the presence of side holes increases patency and reduces premature clogging of biliary stents. Limitations in this study include the fact that it was not randomized and that only 90 stents were studied over a 10-year period [2].