Background and study aims: The biliary stents in current use have a tendency to be blocked, so we designed a self-expandable metal stent covered with polyurethane to overcome the risk of tumor ingrowth of uncovered self-expandable metal stents. To evaluate the success and the effectiveness of the new membrane-covered self-expandable metal stent (covered modified Gianturco biliary stent), we studied patients with biliary obstruction caused by biliopancreatic carcinoma.
Patients and methods: We retrospectively evaluated 47 patients with malignant biliary obstruction to receive either a newly developed self-expandable metal stent covered with polyurethane (21 cases) or an uncovered metal stent (Strecker stent or Wallstent, 26 cases) by the endoscopic transpapillary route.
Results: The success rate of stent insertion and drainage effect of stent showed no statistical difference in patients with a new membrane-covered self-expandable metal stent compared with those with an uncovered metal stent (90.4% vs. 88.5%, P > 0.05; and 100% vs. 95.6%, P > 0.05, respectively). The median patency of the stent was slightly prolonged in patients with a membrane-covered self-expandable metal stent, but there was no statistical difference between two groups (267 vs. 233 days, P > 0.05). The rate of early complication related to stent insertion showed no significant difference between the two groups. During the follow-up period, stent occlusion due to tumor ingrowth occurred in two patients (10.5%) in the membrane-covered, self-expandable stent group, compared with six patients (26.1%) in the uncovered metal stent group. The membrane-covered metal stent was removed successfully and a polyethylene stent was reinserted in one patient who had developed tumor overgrowth.
Conclusions: A new, membrane-covered, self-expandable metal stent has a tendency towards better long-term patency than the uncovered metal stent, and it can effectively prevent tumor ingrowth into the stent. Also it is possible to remove an occluded membrane-covered stent. However, a case-controlled study, including a larger patient number, and long-term follow-up are needed.