Unveiling the Challenges in Tandem Ureteral Stent Management for Malignant Ureteral Obstruction: Failure Rate, Risk Factors, and Durability of Their Replacement

Abstract

Background: Malignant ureteral obstruction (MUO) is a sequela of advanced malignant disease that requires renal drainage, with tandem ureteral stents (TUSs) being a viable option. This study aimed to evaluate the TUS failure rate, associated risk factors, and the feasibility of replacing failed TUSs with a new pair of stents.

Methods: A retrospective analysis of MUO patients treated with TUS insertion from 2014 to 2022 was conducted. TUS failure was defined as urosepsis, recurrent urinary tract infections, acute kidney failure, or new hydronephrosis on imaging. Cox proportional hazard regression analysis identified the independent predictors of TUS failure.

Results: A total of 240 procedures were performed on 186 patients, with TUS drainage failing in 67 patients (36%). The median time to failure was 7 months. Multivariate analysis revealed female gender (OR = 3.46, p = 0.002), pelvic mass (OR = 1.75, p = 0.001), and distal ureteral obstruction (OR = 2.27, p = 0.04) as significant risk factors for TUS failure. Of the failure group, 42 patients (22.6%) underwent TUS replacement for a new pair. Yet, 24 (57.2%) experienced a second failure, with a median time of 4.5 months. The risk factors for TUS second failure included a stricture longer than 30 mm (OR = 11.8, p = 0.04), replacement with TUSs of the same diameter (OR = 43, p = 0.003), and initial TUS failure within 6 months (OR = 19.2, p = 0.006).

Conclusions: TUS insertion for the treatment of MUO is feasible and has good outcomes with a relatively low failure rate. Primary pelvic mass and distal ureteral obstruction pose higher risks for TUS failure. Replacing failed TUSs with a new pair has a success rate of 42.8%. Consideration should be given to placing larger diameter stents when replacing failed TUS.

Keywords: malignant ureteral obstruction; polymeric stents; renal drainage; tandem ureteral stents; ureteral stricture.

Figure 1

Flowchart of patient identification and study groups. TUS = tandem ureteral stents insertion, MUO = malignant ureteral obstruction, PCN = percutaneous nephrostomy tube.

Figure 2

Proportion of tandem ureteral stent drainage success (blue) and failure (red), categorized by primary tumor system. The number of patients is indicated in each box. There were higher rates of failure in gynecological (41.4%) and gastrointestinal (38.6%) malignancies, in comparison to urological (19%), hematological (11%) and others (20%). However, this did not reach statistical significance (p = 0.136).

Figure 3

Kaplan–Meier curves to estimate the success of TUS drainage by (A). Gender (blue—female, red—male); we found a significant success rate in the male group in comparison to the female group (p = 0.001). (B). Primary tumor location (blue—pelvic, red—not-pelvic); we found a significant success rate in the non-pelvic tumor group in comparison to the pelvic tumor group (p = 0.049). (C) Structure location (red—distal, blue—not-distal); although distal structure was found to be a significant risk factor for TUS failure, the survival analysis did not show a higher success rate in the non-distal structure group (p = 0.11).

Figure 4

Kaplan–Meier curve to estimate the success of TUS replacement after a single failure by TUS diameter (blue—same diameter as the TUS that have failed, red—larger diameter). We found a significant success rate when replacing the TUS with a larger-diameter stent (p = 0.011).

Figure 5

Kaplan–Meier curve to estimate the success of TUS replacement after a single failure by stricture length (blue—stricture shorter than 30 mm, red—stricture longer than 30 mm). We found that a stricture longer than 30 mm was related to an earlier second failure, with a median of 4 months (2–5), in comparison to 6 months (5–8) in those with shorter strictures.