Comparison of Yang-Monti ileal ureter-bladder anastomosis versus Yang-Monti ileal ureter-ureteral anastomosis for the treatment of ureteral stenosis: a randomized controlled trial in a miniature pig model
Authors: Zhenxing Wang , Zhaolin Sun , Xiushu Yang , Guangheng Luo , Ye Tian , Lei Shen , Zhiyong Su , Hongming Liu 
Published: December 2019

Abstract
Background
The aim of the present study was to establish an animal model of Yang-Monti ileal ureter-bladder anastomosis and Yang-Monti ileal ureter-ureteral anastomosis and compare the advantages and disadvantages of the two surgical methods.

Methods
Fourteen 12-month-old male Chinese miniature pigs weighing 21 ± 1.38 kg were randomly divided into two groups. Group A (n = 7) underwent end-to-end anastomosis of the left Yang-Monti ileal ureter, left ileal ureter and left lower ureter; group B (n = 7) underwent anastomosis of the left Yang-Monti ileal ureter, left ileal ureter and bladder. In both groups, the contralateral kidney was removed at 1 week postoperatively. The incision length and operation time of the two groups were compared. Changes in serum creatinine and urea nitrogen were observed preoperatively, and at 2, 6 and 12 weeks postoperatively. Venous pyelography and cystography were performed at 12 weeks postoperatively to determine the ureteral patency and vesicoureteral reflux. At 12 months postoperatively, urinary culture was performed, and the diameter and histological changes of the intestinal ureter were assessed.

Results
Surgery was successfully completed in all 14 pigs. In group A, one pig died due to an anesthetic accident, and one pig died from a lung infection on postoperative day 4. In group B, one pig died from adhesive intestinal obstruction on postoperative day 7. The overall survival rate was 78.6%, and the 11 surviving pigs had no urinary or intestinal fistulae. Compared with group B, group A had a significantly longer surgical incision (30.86 ± 2.41 cm versus 26.71 ± 3.64 cm; p = 0.01) and shorter operation time (181.29 ± 15.10 min versus 157.71 ± 20.49 min; p = 0.02). The serum creatinine and urea nitrogen concentrations did not significantly differ between groups. All pigs had normal renal function pre- and postoperatively. There was no stenosis or obstruction on venous pyelography. The narrowest diameter of the ureter was significantly smaller in group B (5.90 ± 0.30 mm) than in group A (7.26 ± 1.06 mm; p = 0.01), but no contrast agent returned to the upper urinary tract in either group. Escherichia coli was detected on urine culture. In group A, one pig had obstruction of the ureteral ureter, while another had stenosis of the lower ureteral anastomosis. In group B, one pig had pelvic and intestinal ureteral dilatation; however, all anastomoses were patent. The ileal ureteral diameter was significantly larger in group A (9.40 ± 2.35 mm) than group B (6.62 ± 0.37 mm; p = 0.02). Two pigs in group A had separation of the transitional epithelium and columnar epithelial mucosa, with granulation tissue hyperplasia. The pigs with stenosis and obstruction had smooth fibrous tissue and smooth muscle of the anastomosis. In both groups, the two types of epithelial tissue were close together, and the intestinal villi were mildly atrophied and shortened.

Conclusions
An animal model of Yang-Monti ileal ureter-bladder anastomosis was successfully established. Compared with Yang-Monti ileal ureter-ureteral anastomosis, Yang-Monti ileal ureter-bladder anastomosis is simpler, more reliable, and results in fewer complications.