The development of a pig model to study fetal vesico-ureteric reflux

Objective To develop a surgical protocol to induce vesico-ureteric reflux (VUR) in utero by ablating the ureteric tunnel in a fetal pig model. Materials and methods Fetal surgery was conducted on nine sows, which were divided into three groups according to changes in the surgical protocol. Sows in groups 2 and 3 received different anaesthetics and antibiotics, and the operating theatre temperature was increased. In all cases, the intramural part of the ureter was unroofed in the fetuses, which were then returned to the uterus. Upon delivery, cystograms were taken in the male piglets, and the urinary tracts removed for anatomical and histological examination. Results All three sows in group 1 delivered healthy piglets, but the fetuses that had undergone surgery were mummified. In group 2 the animals survived the fetal intervention, as shown by ultrasonography after surgery, but the four sows aborted spontaneously within a week. In group 3, both sows delivered normally developed piglets, three of which had undergone ablation of the ureteric tunnel. VUR was present only in those renal units in which the ureteric tunnel was ablated, and this was associated with hydronephrosis, dilatation of the ureters and thinning of the renal parenchyma on gross pathological examination. Conclusions The fetal pig model of VUR not only appears to be feasible, but with similarities in renal anatomy and physiology also seems to be ideal for investigating fetal VUR.