The Application Of Wrapping Ureter By A Pedicled Gastrocolic Omentum Flap Combined With An Artificial External Scaffold To Prevent Stoma Stenosis In Rabbit After Ureterocutaneostomy

Objective:To evaluate the feasibility and mechanism of wrapping ureter by a pedicled gastrocolic omentum flap combined with an artificial ureteral external scaffold to prevent stoma stenosis in rabbit after ureterocutaneostomy.Methods:40 male New Zealand rabbits were involved in this study. For application of ureterocutaneostomy, the right ureter was wrapped by a pedicled gastrocolic omentum flap and combined with an artificial external scaffold, which served as experimental side. Traditional ureterocutaneostomy was applied in left ureter (control side). All rabbits were sacrificed after one month and the kidney, ureter and abdominal segment ureter were collected to study the morphological and pathological changes by using HE staining, Masson staining, Immunohistochemistry staining and microvessel density (MVD) study.Results:In the control side, the specimen morphology shows the ureterectasia and moderate to severe hydronephrosis and the surface of kidney was found to be with high tension and congestion. HE staining demonstrated that renal medullary tubular dilatation, large number of collagen deposition, renal glomerular and renal tubular atrophy, glomerular vascular leaves and interstitial fibrosis were detected in the kidney of control side. However, the abnormities in the kidney of experimental side were significantly lighter than control side. By measuring the thickness of renal cortex, the results showed that the control side of the renal cortex was significantly thinner, the average thickness was 5.61±0.26mm and the average thickness of experiment side was 10.68±0.26mm, there were statistically significant differences between the two sides (P<0.05); The collecting system separation of the kidney in control side was 3.08±0.18mm, which is significantly severe compared to the experimental side (1.06±0.16 mm). The average diameter of ureter in control side was 3.07±0.16mm and the average diameter of ureter in experimental side was 1.06±0.16mm, statistically significant difference was indicated between two sides (P<0.05). Overall,the above results indicated that hydronephrosis in control side is more serious than experimental side. The abdominal ureteral lumen irregular stenosis and pale mucous membranes were observed in control side, which was significantly severe than experimental side. Masson staining showed that the density of collagen fibers in the experimental side of the abdominal segment ureter was 25.54±4.26, and the control side was 42.36±6.04, there was statistically significant difference between two sides (P<0.05). To determine the severity of the fibrosis, we used immunostaining study to measure the expression level of TGF-beta 1. The results showed that the positive expression of TGF-beta 1 rate was 47% in the abdominal ureteral tissue of experimental side and the rate in control side was 100% (P<0.05). The microvessel density in the abdominal segment of the experimental side was 11.48±2.11, and the control side was 5.23±2.09, there were statistically significant differences between the two sides (P<0.05).Conclusions:In this study, we have demonstrated that wrapping ureter by a pedicled gastrocolic omentum flap combined with an artificial external scaffold is capable of preventing stoma stenosis in rabbit after ureterocutaneostomy, which provided a new method and theoretical basis for clinical application in the future.