Analysis of bladder histology and urodynamics in female rats submitted to bladder reconstruction with rectus abdominis muscle.

Introduction: Bladder histology and measures of maximal bladder pressure and maximal bladder volume during urinary loss in female rats submitted to bladder reconstruction with a myoperitoneal flap of rectus abdominis muscle were studied.

Materials And Methods: Fifty female adult Wistar rats were studied, separated in 5 groups: Group 1 (immediate): submitted to laparotomy, cystostomy, and cystometry; Group 2 (sham): submitted to laparotomy, anterior bladder wall incision, immediate suture and cystostomy; Group 3 (cystectomy): laparotomy, partial cystectomy, cystostomy; Group 4 (cystoplasty): midline laparotomy, partial cystectomy, augmentation with rectus abdominis muscle flap peritonized, cystostomy, total cystectomy, the rats were sacrificed and an histological study of the augmented bladder performed; Group 5 (cystostomy): midline laparotomy and cystostomy. Cystometry was always performed in post-operative day 7, excepting for Group 1. Assessment was comparative maximal bladder pressure and maximal bladder volume during urinary loss among the different groups.

Results: In cystoplasty group, mean maximal bladder pressure during urinary loss was lower than in immediate, sham, and cystostomy groups. It was also observed that maximal bladder volume during urinary loss presented mean and median values very close in each group, and cystectomy group showed much lower values. The group submitted to cystoplasty presented mean maximal bladder volume during urinary loss higher than all groups analyzed. Histological analysis of myoperitoneal flap augmented bladders showed partial and/or total epithelization in the muscular flap interspersed region with transitional cells, squamous metaplasia region and chronic inflammatory process.

Conclusion: The use of peritonized rectus abdominis muscle flap to perform bladder augmentation was technically viable in the animals, showing urothelial epithelization in the muscular region of the flap, and a satisfactory gain of capacity and maintenance of low bladder pressures.