Lack of usefulness of ureteral reconstruction with free bladder mucosa flap in dogs confirmed by microangiography

BACKGROUND There is a paucity of data addressing the blood supply in the surgically reconstructed ureter, and complete lack of microangiographic studies of the reconstructed ureter with the use of a free bladder mucosa flap. The present study evaluated the blood supply in the reconstructed dog ureter after a 5-centimeter segment resection, supplemented by a tube constructed from a free bladder mucosa flap. MATERIAL AND METHODS Female mongrel dogs (n=29) were used in this study. Under general anaesthesia, a 5-centimeter autologous free bladder mucosa flap was used to construct a tube, which was afterwards grafted to replace a 5-centimeter ureter resection. After a period of 3 months (n=2) and after 1 year (n=2), microangiography was performed to assess the revascularization of the grafted ureter. RESULTS In our study, we observed the continuity of the ureter, but the grafted reconstruction was narrowed by the cicatrization in about 86% (n=25) of cases. This resulted in the development of hydronephrosis, as described in previous publications. The ureteral wall was covered by a normal urothelium, but consisted of fibrous connective tissue, which failed to restore a regular (normal) coat. The reconstructed segment showed no smooth muscle cells. A few smooth monocytes were found only at the border with intact portions of the ureter. The microangiography performed at the end of the experiments showed no vascularization of the restored segment of the ureter. CONCLUSIONS The experiments showed a whole regeneration of urothelium in the transected and reanastomosed ureters. However, there was no regeneration of the muscular coat and a complete lack of revascularization.