The thermoexpandable nitinol stent: a long-term alternative in patients without nephropathy or malignancy.

Objective: The aim of this study was to investigate the long-term outcome of a thermoexpandable nickel-titanium nitinol ureteral stent (Memokath 051) and to identify individual risk factors for failure.Materials and methods: This retrospective single-centre study included 125 patients who underwent implantation of the self-expandable Memokath 051 stent. Complications, indwelling time and reason for explantation were recorded. Analyses were stratified by gender, age, body mass index, American Society of Anesthesiologists score, estimated glomerular filtration rate (eGFR), side, localization and cause of the stricture.Results: In total, 91 out of 125 patients (73%) were available for analysis. Median indwelling time was 355 days (range 7-2125 days). Most stents were removed because of dislocation (42%) or occlusion (40%). Stent removal was rarely performed because of infection (3%). Patients with sufficient renal function (eGFR 60ml/min/1.73m(2)) showed increased indwelling times compared with those with nephropathy (386 vs 317 days; p<0.01). Patients with active malignant disease showed reduced patency time compared with strictures of benign origin (455 vs 190 days; p<0.01).Conclusions: This thermoexpandable nitinol stent offers safe mid-term treatment of ureteric strictures, especially in patients without active malignancy and with good renal function.