Changes in bladder of rabbits subjected to elevation of intraabdominal pressures

Background/Purpose: An experimental study has been conducted to evaluate th e effects of increased intraabdominal pressure (IAP) on the morphology of t he bladder of rabbits. Methods: Experiments were performed on 20 adult male New Zealand rabbits. S ix rabbits served as the control group (group I). Seven rabbits were subjec ted to increased IAP of 7 cm H2O for 10 days through installing air into th e abdominal cavity (group II). Increased IAP was maintained for 60 days in another group of 7 rabbits (group III). Bladders were removed and fixed in 10% formalin for routine process. Paraffin sections of 5 to 7 mum were stai ned with H & E far light microscopic evaluation. Histopathologic parameters were scored, and the mean scores according to groups were compared by 1-wa y analysis of variance (ANOVA). The mean values of groups were compared sep arately by Tukey-Kramer multiple comparison test. In these tests, P value l ess than .05 was considered statistically significant. Results: All of the bladder strips obtained from animals subjected to 10 da ys of pressure increase (group II) showed mild to severe degree of vacuolat ion and desquamation of urothelium. Both vacuolation and desquamation of ur othelium were present in all of the strips obtained from rabbits with 60 da ys pressure increase (group III). Additionally, there were infiltration and congestion of the urothelium together with vacuolation, suburothelial edem a, and desquamation in 4 group III rabbits. Moderate or severe congestion i n the lamina propria was present in bladder strips of group II rabbits. The congestion of the lamina propria was advanced, and additional moderate to severe inflammation was present in 4 rabbits of group III. Mean histopathol ogic scores of urothelium (B < .00001) and lamina propria (P = .002) differ ed significantly among groups. When the groups were compared one by one, th e differences between the group I and group II and group II and III were si gnificant (P < .05). Although seroza appeared normal in both group I and II , moderate congestion and infiltration of the seroza was present in the bla dder strips of group III (P < .05). Conclusion: Increases in IAP for even 10 days show damaging effects on the bladder. Extended period resulted in augmentation of the damage. Copyright (C) 2001 by W.B, Saunders Company.