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DOI: 10.1055/s-2002-35300
Endoscopic Retrograde Cholangiopancreatography
Publication History
Publication Date:
13 November 2002 (online)
Biliary Stenting
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].
A retrospective analysis of 120 patients with stents (34 metal, 26 double-layer, 60 standard plastic) placed for malignant biliary stenosis reports that standard plastic stents appeared to occlude earlier. When metal and double-layer stents were compared, however, no significant differences in the rates of occlusion or time to occlusion were noted [3].
Future prospective studies should evaluate the patency and cost-effectiveness of these new stents in comparison with metal stents in malignant stenoses. It is conceivable that patients with a moderately reduced life expectancy may benefit from the cheaper double-layer stents.
Another study compared plastic and expandable metal stents in the palliation of malignant obstructive jaundice. The median time of patency for the metal stent group was 148 days vs. 63 days for the plastic stent group (P < 0.05). When the costs of repeat endoscopic retrograde cholangiopancreatography (ERCP) procedures and of the stents were assessed, the cost per day of patency was €30 euros for plastic stents and €19 euros for metal stents, suggesting that the latter are more cost-effective [4].
Covered metal stents are undergoing evaluation for malignant biliary obstruction, with several studies suggesting a decreased incidence of occlusion [5]. The type of covering is important, with silicone appearing to be superior to polyurethane [6]. A prospective randomized study of covered (polyurethane) vs. uncovered expandable metal stents in malignant biliary obstruction (112 patients) showed that stent occlusion was significantly less frequent in the covered stent group (12 % vs. 36 %) [7].
Bio-absorbable self-expanding biliary stents are being developed and were placed successfully in pigs, with promising preliminary results [8]. Other preclinical devices include “push-me-pull-you” plastic stents that are locked to the pushing mechanism. These stents can be pulled back easily when inserted too far. When the position is correct, the lock is released [9].
The endoscopic treatment of post-laparoscopic cholecystectomy bile duct lesions is now well documented. In one study, 65 % of patients with lateral common bile duct injury were successfully treated endoscopically, with stents removed after 1 year. Follow-up ranged from 17 to 114 months. Seventy-eight percent of patients with late-appearing strictures were successfully treated endoscopically (follow-up 14 to 108 months). The length of follow-up suggests that the effect of endoscopic dilatation therapy can persist for many years. Parallel stenting was used in about 20 % of cases [10].
