Comparison of MemoKath™ ureteral stent versus tumor ureteral stent: A single-center long-term analysis

The MemoKath™-051 (MK) is a thermo-expandable spiral stent for the treatment of benign or malignant ureteral obstruction. Existing studies on outcome measurements, like complication rate or time to stent exchange for MK differ significantly. In this retrospective analysis, we investigated the supposed superiority of the MK over conventional tumor ureteral stent (TUS) insertion.

In this monocentric retrospective analysis, 72 consecutive patients with benign or malignant extrinsic ureteral stenosis who either underwent insertion of a MK or TUS between 03/2008 and 12/2018 were analyzed. Indications for stent insertion were either chronic benign or malignant extrinsic obstruction in patients who were unsuitable for or refused definitive surgery. Patients who underwent urinary diversion were excluded. We compared the indwelling time, the complication rates and the time to occurrence of complications using Mann-Whitney-U-test and χ² test for categorical variables. Complication rates of both, the MK and the TUS were compared using Fisher´s test. Complications were classified according to Clavien-Dindo Classification (CDC).

The total number of ureteral units analyzed was 171, including 89 MK stents and 82 TUSs. No significant differences between both groups regarding age, stent indications, and stricture characteristics occurred. At a median follow-up of 32 and 27 months in the MK and TUS groups, postoperative complications occurred in 82 (92%) and 19 (23%) patients, respectively (p = 0.01). Almost all complications were major (CDC grade 3b) that required stent removal or replacement, with the exception of one patient in the MK group. Median time to complications was significantly longer for the MK group, 5.6 months, compared to 3.5 months in the TUS group (p = 0.01), and median time to stent replacement was 8 months for the MK group vs 5.2 months for the TUS group (p <0.001).

Although the MemoKath™ is designed for a long indwelling time of up to years, it is associated with higher complication rates and premature replacement. However, compared to the TUS, the MK still has a significantly longer indwelling time. Further studies are needed to determine the predictors of failure and the best candidates for both stents.