Establishment of Mini-pig Model of Ureteral Stricture by Electrocoagulation Under Ureteroscopy.

OBJECTIVE: To establish a mini-pig model of ureteral stricture by using electrocoagulation under ureteroscopy. METHODS: Twelve female mini-pigs were included. Their ureters on one side and contralateral side were randomly divided into electrocoagulation and control groups, respectively. In the electrocoagulation group, the middle ureter was circumferentially electrocoagulated by using a self-made electrocoagulation device with the ureteroscope under direct vision, while the control group underwent ureteroscopy only without electrocoagulation. At 30 and 90 days after electrocoagulation, the glomerular filtration rate (GFR), formation of ureteral stricture, and histomorphological changes of ureteral tissues of each group were detected. RESULTS: At 90 days after surgery, ureteroscopy and retrograde urography revealed ureteral stricture formation in the middle ureter in the electrocoagulation group. GFR was gradually decreased over time with prolonged washout half-time in the electrocoagulation group. A compensatory increase in GFR was observed in the control group. Hematoxylin and eosin staining and Masson's Trichrome staining revealed fibroblast infiltration and fibrous tissue hyperplasia in the superficial muscular layers, and the muscular layers were arranged disorderly in the electrocoagulation group. Immunohistochemical staining showed accumulation and disorganization of ureteric epithelium in the narrow segment. In the control group, the epithelium was arranged neatly with normal structure. CONCLUSION: A mini-pig model of ureteral stricture was successfully established using electrocoagulation under ureteroscopy. This method has the advantages of being simple to implement, having high accuracy and high success rate, which can provide an ideal animal model for studying ureteral stricture.