Introduction: Chronic ureteral stricture and ureteral fistula are treated with urinary diversion using percutaneous nephrostomy or double pigtail stent. Both of these techniques require replacement of the tube every few months in order to prevent encrustations and obstruction.

Objectives: To report the long-term efficacy of the new Allium Ureteral Stent (URS) in the treatment of ureteral stricture and fistula.

Methods: The Allium URS is a newly-developed ureteral stent made of nickel-titanium (Nitinol), which is inserted in a small diameter and spontaneously expands into and preserves a large-caliber. The stent is coated with a biochemical co-polymer which prevents tissue ingrowth and incrustations. The stent is inserted antegradely or retrogradely with intraoperative x-ray guidance after dilation of the stricture. The Allium URS stent was inserted into 107 ureters of 92 patients in 5 different centers worldwide; 69 patients carried a percutaneous nephrostomy before the procedure and 38 patients had a ureteral stent. The etiologies underlying the strictures were: gynecological cancer (with or without irradiation), bladder cancer, iatrogenic stricture, ureteroileal stenosis, stricture following uretero-pelvic junction obstruction repair and iatrogenic ureteral fistula.

Results: During a mean follow-up of 27 months, only one stent was obstructed after eleven-indwelling months; 21 patients died of their primary disease carrying the stent. Stent migration was seen in 11 patients within 8 months after its insertion, and these stents were removed. In 4 patients with early stent migration, the stents were replaced. In 18 patients the stents were removed as planned after one year of indwelling time, and these patients were asymptomatic in a follow-up period of up to 59 months.

Conclusion: The results of our study show that the use of Allium URS for the treatment of ureteral strictures is feasible, safe and effective. The relative ease of its insertion could encourage its use in a wide range of other indications.

Discussion: Due to its unique structure, the Allium URS is superior to the regular pigtail stents in the treatment of ureteral strictures. Stent migration was seen in only 10.7% of the patients, mainly in patients with stricture of the mid-ureter.

Summary: The use of the Allium URS stent in the treatment of proximal and distaL ureteral strictures is safe and effective.