Introduction: The success rate of drainage with tandem ureteral stents (TUS) for malignant ureteral obstruction (MUO) is 72-87%. Failure of TUS is usually followed by the insertion of a percutaneous nephrostomy tube (PCN). The objective of this study was to examine the possibility of replacing the first-time failed TUS with a new pair of TUS- the success rate of the procedure, and the risk factors for a second failure. Methods: The medical records of all patients with MUO who underwent balloon dilation and TUS insertion in our institution between 2014-2022 were retrospectively analyzed. Failure of TUS was defined as an episode of urosepsis, recurrent urinary tract infections, acute kidney failure, or detection of new hydronephrosis on imaging scans. Independent risk predictors of failure of secondary TUS were determined by a multivariate cox regression analysis. Results: 240 procedures were performed on 186 patients during the study period. 67 (36%) patients failed for the first time after a median follow-up time of 7 months (IQR 4-17). Of which, 25 (37.4%) patients were drained by a PCN, and 42 (62.6%) were treated by exchanging the TUS with a new pair. Among the patients who underwent a second TUS insertion, 18 (42.8%) did not fail again, and continued to enjoy timely replacements of the TUS. However, 24 (57.2%) patients did fail for the second time and were drained via PCN. In a multivariant analysis, we found that inserting the same diameter TUS as the pair that failed (p=0.002) and time to first failure =6 months (p=0.006) were significant risk factors for a second failure of TUS. Cox regression analysis found that distal ureteral stricture predicts shorter time to second failure. During the study period, the group that didn’t fail for a second time underwent 73 replacements of TUS overall (4±2.3 procedures per patient) in a median follow-up time of 19.5 months. Conclusions: The success rate of replacing TUS after its failure is 42.8%. When replacing failed TUS, one should consider larger-diameter stents. SOURCE OF Funding: None
