Thermal radiofrequency induced porcine ureteral stricture: A convenient endourologic model

Purpose: To establish a reliable model of iatrogenic ureteral stricture mim icking the human clinical situation in order to experiment with new site-sp ecific endourologic treatment concepts. Materials and Methods: After cystoscopic insertion of a 7F right ureteral c atheter, we induced external thermal radiofrequency injury to the right upp er third ureter at low power setting (10 W) using an open surgical approach in 13 pigs. Three pigs considered as controls underwent the same procedure without application of electrocautery. All 16 animals were initially asses sed at 8 days; 3 study animals and the 3 controls were followed for 6 weeks . Results: No control animals had strictures. Significant upper third uretera l strictures with marked hydronephrosis where achieved in all study animals after a mean interval of 9 days, as evidenced by ultrasound examination an d retrograde ureteropyelography. Endoscopic retrograde access to these stri ctures was always possible (mean length 1.4 cm.). Histologic examination di splayed severe disorganization of the muscular layer by dense fibrosis comp osed of collagen bundles with few scattered fibroblasts. No spontaneous imp rovement of the stricture was observed in the 3 animals reassessed at 6 wee ks. Conclusions: Externally applied radiofrequency energy to porcine ureter pro vides a reproducible model of fibrous stricture resembling its clinical cou nterparts.