Membrane Degradation of Covered Stents in the Upper Gastrointestinal Tract: Frequency and Clinical Significance

Purpose: To evaluate the frequency, clinical significance, and predictive factors of membrane degradation of covered stents in the upper gastrointestinal (UGI) tract. Materials and Methods: From 1996 to 2006, 166 stents were removed from 151 patients. Indications for stent removal included temporary stent placement for esophageal cancer before radiation therapy or radiation-chemotherapy (n = 53), stent migration (n = 40), temporary stent placement for a benign UGI stricture (n = 32), pain (n = 21), recurrent obstruction (n = 16), incomplete stent expansion (n = 1), recurrent transesophageal fistula (n = 2), and aspiration (n = 1). Removed stents were examined to evaluate possible causes of membrane degradation. Multivariate analysis was performed to determine the predictive factors of membrane degradation. Results: Degradation of the covering membrane occurred in 14 of the 166 stents (8%). Recurrent obstruction due to tumor ingrowth (n = 7) and reopening of the transesophageal fistula (n = 1) through the degraded membrane occurred in eight stents (5%). At multivariate logistic regression analysis, the type of covering membrane (P = .018), stricture location (P = .006), and duration of stent placement (P = .002) were significantly associated with degradation of the covering membrane. Conclusions: Degradation of the covering membrane after stent placement in the UGI tract is not an uncommon event, and recurrent obstruction or fistula can occur through the degraded membrane. A polyurethane membrane is not biostable and dissolves over time, particularly in the gastroduodenal area.