Single-Center Experience with Three Metallic Ureteral Stents (Allium® URS, Memokath™-051, and Resonance®) for Chronic Ureteral Obstruction

Purpose: Patients with chronic ureteral obstruction (CUO) are traditionally managed with polymer stents/nephrostomy. However, these are prone to failure and require regular exchange. This study evaluates the efficacy of Allium® URS, Memokath™-051, and Resonance® metallic ureteral stents in managing patients with CUO. Methods: Following institutional approval (Imperial College Healthcare NHS Trust, UK, Registration Number SPS_045), operating theater records were reviewed to identify patients with CUO managed with Allium® URS, Memokath™-051, or Resonance® metallic ureteral stents (September 2015/July 2020). Baseline patient variables (age, gender, underlying etiology, and American Society of Anesthesiologists score) and stricture characteristics (length, level, and continuity) were extracted. Intraoperative and postoperative clinical and radiologic assessments at 6 weeks, 3 months, and then every 6 months, as well as any emergency attendances, were reviewed. The primary outcome was duration of functional stent survival. Secondary outcomes included intraoperative placement success and, as an estimate of renal function, mean serum creatinine over time. Results: One hundred twenty-nine stent insertion episodes (SIEs) (Allium® URS: 23; Memokath™-051: 48; Resonance®: 58) occurred in 76 patients (Allium® URS: 16; Memokath™-051: 31; Resonance®: 29). Kaplan-Meier estimates demonstrated that Resonance® provided superior functional stent survival. Overall median actual functional stent follow-up was 11.4 months for Allium® URS, 5.5 months for Memokath™-051, and 11.7 months for Resonance®. 47.8% of Allium® URS (11/23), 64.6% of Memokath™-051 (31/48), and 19% of Resonance® SIEs (11/58) failed. No Resonance® SIEs for benign indication ended in failure. Intraoperative placement success was high (Allium® URS: 95.7%; Memokath™-051 and Resonance®: both 100%). In the first year following SIE, creatinine ranged from +21.3% to +46.7% for Allium® URS, -7.8% to +8.9% for Memokath™-051, and -9.4% to +27.3% for Resonance®. Conclusions: Allium® URS, Memokath™-051, and Resonance® metallic ureteral stents are all viable management options of CUO. In this cohort, Resonance® provided superior functional stent survival. Prospective large-scale comparisons with long-term follow-up are needed to help inform stent choice dependent on individual patient and stricture characteristics.