Evaluation of a novel temperature-sensitive polymer for temporary ureteral occlusion

Purpose: Proximal stone migration during ureteroscopic procedures increases operative time and risk. This study was designed to evaluate the ability of a new temperature-sensitive polymer to prevent proximal stone migration during ureteroscopic procedures. Materials and Methods: Porcine urinary systems were harvested en bloc. The volume of gel needed to occlude the ureter, time to achieve a solid state, length of ureter filled, and pressure needed to dislodge the gel from the ureter were recorded. Radio opacity of the polymer was evaluated. Endoscopic laser lithotripsy was the performed after deploying the urologic polymer, and, after gel application and stone manipulation, all ureters were examined for histologic changes. Results: At 36.7°C, 0.5 mL and 1 mL of polymer sufficiently occluded the ureter. Both amounts solidified in 25 to 40 seconds. The mean length of ureter occluded was 56.3 mm, and the mean pressure needed to dislodge the polymer was 159.2 mm Hg. The polymer was radiopaque and did not cause histologic alterations in the ureter. Proximal migration of stone fragments was not observed during any of the procedures performed. Conclusions: Our in vitro study indicates that this radiopaque, thermosensitive polymer is able to transiently occlude the ureter without damaging the urothelium while withstanding the pressure of ureteroscopic irrigation, stone motion, and laser energy.