Thermal radiofrequency induced porcine ureteral stricture: a convenient endourologic model

To establish a reliable model of iatrogenic ureteral stricture mimicking the human clinical situation in order to experiment with new site-specific endourologic treatment concepts.

After cystoscopic insertion of a 7F right ureteral catheter, we induced external thermal radiofrequency injury to the right upper 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 assessed at 8 days; 3 study animals and the 3 controls were followed for 6 weeks.

No control animals had strictures. Significant upper third ureteral strictures with marked hydronephrosis where achieved in all study animals after a mean interval of 9 days, as evidenced by ultrasound examination and retrograde ureteropyelography. Endoscopic retrograde access to these strictures was always possible (mean length 1.4 cm.). Histologic examination displayed severe disorganization of the muscular layer by dense fibrosis composed of collagen bundles with few scattered fibroblasts. No spontaneous improvement of the stricture was observed in the 3 animals reassessed at 6 weeks.

Externally applied radiofrequency energy to porcine ureter provides a reproducible model of fibrous stricture resembling its clinical counterparts.