Pathogenetic factors in vesico-ureteral reflux. A longitudinal cystometrographic study in pigs.

In a cystometrographic study in 36 young pigs the importance of ageing, of the submucosal part of ureter, and of infravesical obstruction in the vesico-ureteral reflux pathogenesis was investigated. Spontaneous vesico-ureteral reflux was found in 13 of the pigs (23 ureters). As the pigs grew older, the reflux disappeared, but if an infravesical obstruction was superimposed the reflux was maintained in half of the pigs. When the intravesical submucosal ureter was unroofed, vesico-ureteral reflux was present 10 weeks later in half of the cases. If an infravesical obstruction was superimposed all the pigs had sustained reflux 10 weeks later. The reflux producing bladder pressures decreased after induction of an infravesical obstruction. This suggests irreversible damage to the valve function due to the obstruction. In conclusion, the present study confirms ageing and the valve function as important factors preventing reflux. Additionally, it stresses the importance of normal bladder urethral function in preventing reflux.