Influence of surgical bladder reduction on urodynamic parameters: three techniques investigated in a rat model

Bladder wall wrapping and invagination have been used for the surgical treatment of the underactive detrusor and improvement of bladder emptying has been described. In a rat model we investigated the evolution in time of urodynamic parameters after 3 techniques of surgical bladder reduction.

Female Wistar rats underwent at random, a bladder reduction with vertical wrapping, the horizontal variant or invagination of the wall. Cystometry was performed before and 30 minutes after surgery, and after 1, 5 and 10 weeks. Sham operated animals had cystometries performed at day 1 and after 1, 5 and 10 weeks. At week 10 contraction of four differently orientated detrusor strips was examined in vitro. A histological study was done.

Contraction pressure was not improved in vivo after 10 weeks follow-up. Capacity, despite an early significant reduction, became slightly higher than presurgery in both wrapping groups and even significantly higher in the invagination group. In each group residual volume almost doubled. In vitro some strips containing operated parts did contract more strongly than controls but not significantly. Strips which contain operated parts showed slightly increased fibrosis in the invagination and the vertical wrapping group and a huge amount of fibrosis in the horizontal wrapping group.

This experiment indicated that the rationales behind the techniques of surgical bladder reduction are not correct. The partial successes in men may be explained by the original intrinsic deficiencies of the detrusor which prevent a secondary bladder enlargement as reaction to the volume reduction.