Assessment of the Grades of Vesicoureteral Reflux in Stented Ureters: An Experimental Study

The aim of this experimental study is to assess, in a porcine model, the onset and grades of vesicoureteral reflux associated with ureteral stents.

Twenty-four female porcine models were used. A 4.7-Fr ureteral stent was placed in all right ureters and kept in place for 6 weeks. Follow-ups were performed on weeks 1, 3, 6, and 12. Ultrasonography, cystoscopy, and fluoroscopy were used to analyze grade of hydronephrosis, presence and grade of vesicoureteral reflux, bacteriuria, and macroscopic changes of the ureteral orifices. Vesicoureteral reflux was classified using a modification of the International Reflux Study Committee grades.

91.7% animals present vesicoureteral reflux, 89.5% grade IA, 3.5% grade IB, and 7% grade II. There is a significant increase in reflux during follow-ups at 3 and 6 weeks, whereas 6 weeks after removal, 26.3% of the ureters still present vesicoureteral reflux. Hydronephrosis and macroscopic changes of the ureteral orifice increase significantly with stenting, but there is no significant association between them and vesicoureteral reflux; the relationship between bacteriuria and the presence of vesicoureteral reflux is not significant either.

Vesicoureteral reflux caused by ureteral stents in an animal model is mostly low grade and mainly affects the distal ureter.