Efficacy and Safety of Self-Expandable Covered Metallic Stents for Benign and Malignant Ureteral Obstructions: A Long-Term Retrospective Study

Background and Objectives: This study evaluated the safety and efficacy of long-term indwelling self-expandable covered metallic stents (UVENTA; Taewoong Medical Co., Ltd., Seoul, Republic of Korea) used to manage benign and malignant ureteral strictures. Materials and Methods: We retrospectively identified and analyzed the medical records of all patients who underwent metallic stent insertion at our institution since September 2012. Additionally, we evaluated the technical and clinical success rates and complications of patients who underwent follow-up for more than 36 months. Results: A total of 25 patients underwent metallic stent insertion for ureteral obstructions at our institution. Among them, 18 underwent follow-up for more than 36 months. A total of 21 ureters (15 unilateral and 3 bilateral) were ultimately included in this study. Metallic stents were successfully placed in all ureters using a retrograde approach, with a technical success rate of 100%. The mean follow-up duration was 58.6 months (range, 36-107 months). However, the clinical success rates were 85.7% (18/21 ureters) by 12 months, 61.9% (14/21 ureters) by 24 months, and 52.4% (11/21 ureters) after 36 months. During follow-up, obstructions could not be resolved using metallic stents in eleven ureters (median time to failure, 18.4 months; range, 2-40 months); therefore, they were treated with nephrectomy (three ureters because of a nonfunctional kidney) or percutaneous nephrostomy and double J stent placement (four ureters). Major complications included the encrustation of the metallic stent, flank pain, and gross hematuria. A uretero-enteric fistula occurred in one ureter. In two patients, existing metallic stents were removed and patency was maintained. In another two patients, new metallic stents were inserted without complications. Conclusions: Benign and malignant ureteral obstructions may be treated effectively and safely with metallic stents. However, the patency rate drastically decreased and major complications occurred during long-term follow-up. Therefore, careful patient selection is necessary to achieve better results.