The effect of bladder diverticula on bladder function: An experimental study in rabbits.

OBJECTIVE: This study aims to evaluate the effect of bladder diverticula (BD) on bladder function using a rabbit model, based on urodynamic findings. METHODS: A total of 32 New Zealand white rabbits were randomly assigned to four groups: (1) sham surgery; (2) a single, 1-cm-diameter BD; (3) a single, large, 3-cm-diameter BD; and (4) four (multi) 1-cm-diameter BD. Urodynamic evaluations were performed preoperatively, and 1week and 1month postoperatively, to measure the postmicturition residual (PMR), maximum bladder capacity (MBC), filling and voiding detrusor pressure (Pdet), compliance, and unstable detrusor contractions. At the end of the study, the animals were sacrificed and assessed for pathologic evaluation and stone formation. RESULTS: In groups 3 and 4, the rabbits all had PMR. At 30days postsurgery, the MBC was found to be 28% and 31% lower than the reference range in groups 3 and 4 and compliance was decreased (p<0.05). Further, the filling Pdet was significantly higher for large and multiple BD than in the 1-cm diverticula or sham groups (6.33±1.73, 4±1.26, p=0.0001). Groups 3 (62%) and 4 (50%) had unstable detrusor contractions. There was also a muscular/collagen ratio increase in the large and multiple BD groups. Four rabbits in the large group and one rabbit in the multiple BD group exhibited stone formation. CONCLUSIONS: Large or multiple BD can alter bladder storage and emptying, and can decrease the capacity of the bladder and reduce its elasticity. Large or multiple bladder diverticula can lead to involuntary contractions, causing dysfunctional voiding.