Tandem Polyurethane Stents Compared to Single Silicone Stent for Malignant Ureteral Obstruction

Malignant ureteral obstruction (MUO) is an extrinsic ureteral obstruction caused by malignant diseases. MUO may induce renal failure, which would be a barrier to several therapies including chemotherapy. Indwelling double-pigtail polymeric ureteral stent is a common method to release renal obstruction, but does not necessarily guarantee renal decompression as most studies reported stent failure with a mean of 30% at a mean time of three months [1-3]. Various endoscopic strategies have been proposed to increase time to failure, including tandem polymeric stents, metallic spiral coil stent, self-expanding Nitinol stent and polymeric stents with different lumen diameter and stiffness [4-7]. However, heterogeneity of MUO, low number of patients, unspecified polymer type, retrospective studies and the lack of a standard method to assess stent failure limit robust comparative analysis.

Tandem ureteral stents (TUS) technique uses two polymeric ureteral stents passed simultaneously to better withstand the presumed compressive forces that overcome conventional single stent. This method offers an additional parallel lumen and allows more extraluminal flow between the two stents [6].

In a study on TUS in 39 renal units with MUO, two 6 Fr stents were inserted. Stent failure, defined by flank pain with increasing creatinine level or worsening hydronephrosis during 3 months after stents insertion, was occurred in 4% of cases [7]. This low failure rate compares favorably with the reported rates with single 6Fr polymeric stent or metallic stent. However, stents irritation, defined by profound lower urinary tract symptoms or renal colic in the absence of worsening hydronephrosis or infection, was reported in 29-85% of patients [7,8].

Silicon stent, which is considered biocompatible and soft, has the potential to be less irritative. In a recent systematic review, silicone stents has less stent-related symptoms in comparison to non-silicone polymers and ''hard'' stents. [9]. However, silicone has high susceptibility to compression, which in case of MUO may results in lower drainage efficacy.

This study aim to compare tandem 6 Fr Percuflex™ stents and single large-caliber 8Fr silicone stent in patients with MUO. The primary endpoint is stent failure rate. The secondary endpoints are patient comfort, quality of life and overall survival.