AN EXPERIMENTAL STUDY OF THE INFLUENCE OF DILATATION AND INCISION TO VESICOURETERAL JUNCTION IN RABBITS

Abstract

The influence of dilatation and incision to vesicoureteral junction in rabbits was studied radiologically and histopathologically. Each 12 Japanese white rabbits were submitted to one of the following procedures to the left ureteral orifice.
1) Dilatation up to 10F
2) Dilatation up to 7F
3) Incision of submucosal ureter
As for the radiological examination, cystography and IVU were performed on the 1st and 3rd days and in the 1st, 2nd, 4th and 8th weeks after operation. In the radiological examination, VUR was observed in 8 of 12 amimals in 10F dilatation group. Dilatation of the upper urinary tract was seen in 10 animals including 4 without VUR. No VUR was observed in the 7F dilatation group and incision group.
As for the histopathological examination, the bladder and ureter were excised after radiological examination. In the 10F dilatation group, damage and fibrosis of intramural ureteral muscle layers were observed, which might be due to laceration of the ureteral wall by excessive dilatation. Furthermore, the area of muscle layers in a cross section of the intramural ureter was significantly decrased in the 10F dilatation group compared with control (p<0.01). In the 7F dilatation group and incision group, histopathological change of the interamural ureter were insignificant.
Comparing the human ureter with the rabbit ureter, 7F dilatation in the rabbit is comparable to 16F dilatation in humans which is the maximum size dilatation in ordinary cases of dilatation of the ureteral orifice. While, 10F dilatation in rabbits is comparable to the extraordinarily huge 24F dilatation in humans.
In conclusion, it is suggested, from the present experiment using rabbits, that the usual procedure of dilatation and incision to the vesicoureteral junction in humans seems to have insignificant influence on the urinary tract.