Experience with Memokath 051 ureteral stent

Objective. The Memokath 051 is a thermo-expandable titanium-nickel spiral developed for long-term ureteral stenting. The aim of this study was to investigate the drainage and safety aspects of this stent. Material and methods. A total of 334 consecutive patients were included: 22 had benign strictures, five had post-irradiation strictures and seven had malignant strictures. Follow-up visits took place after 1 month and thereafter every 3 months for at least 1 year. Results. Thirty-three patients had a total of 37 stents inserted uni- or bilaterally. Pre-insertion dilatation was impossible in one patient and difficult in two, all of whom had post-irradiation strictures. Insertion was complicated in seven patients and uneventful in the other 26. Fifteen stents were in place and functioning with no discomfort or complications at death or the end of follow-up (median 14 months; range 3-30 months), while 22 were non- functioning after 1 day to 16 months (median 5 months). Of these 22 stents, 10 had migrated and 12 were malfunctioning. Among the latter, stricture length was underestimated in four patients, and the stents were replaced successfully shortly after insertion. Four stents were occluded by stones after 1-10 months. No tissue ingrowth was seen. Stent removal was easy, with the exception of one patient with stent calcification. Conclusions. The Memokath 051 is an alternative for selected patients with non-curable ureteral obstruction but is not suitable for use in patients with functional stenosis or stone formation. Insertion and removal are easy in most patients, but can be difficult or impossible, especially in patients with post-irradiation strictures and retroperitoneal fibrosis. Migration and obstruction can occur and careful follow-up is necessary.