A non-open surgical rabbit model of ureteral stricture induced by transurethral endoscopic thermal injury

Iatrogenic thermal injury during endoscopic procedures is a predominant cause of benign ureteral strictures. Existing models rely either on costly large animals, unsuitable for large-scale screening, or on open surgery in small mammals, which causes substantial trauma and high complication rates. We established a rabbit model of ureteral stricture via transurethral endoluminal thermal injury, without open surgery. Under fluoroscopic guidance, endoluminal low-power bipolar electrocoagulation (10 W, 2 s; 20 J) was applied through a flexible ureteroscope. Stricture, defined as histological luminal narrowing with ipsilateral hydronephrosis, was induced in 10/10 rabbits versus 0/10 in both open-surgery models (P < 0.001). Histopathology confirmed collagen deposition, myofibroblast activation and renal tubular injury, while imaging demonstrated obstruction with hydronephrosis and delayed contrast excretion. The endoscopic approach shortened operative time (27.6 ± 6.7 versus 81.6 ± 12.6 and 111.4 ± 14.8 min, P < 0.001) and reduced urinary extravasation and hematuria versus transection–anastomosis (both P = 0.033); mortality (0% versus 30.0% and 40.0%; P = 0.211 and 0.087) and the overall complication rate (10.0% versus 60.0%; P = 0.057) were lower but not significantly so. This model provides a low-cost small-animal platform for large-scale preclinical studies.