[Mechanical changes of the detrusor after antiincontinence surgery].

Background: Stress urinary incontinence is secondary to an intrinsic defect in the closure or a lack of urethral support; the treatment is surgical and this may affect vesical voiding by creating an obstruction, modifying the contraction power at opening and the mechanical properties of the detrusor.

Objectives: To know if there are changes in the contractile characteristics of the detrusor in order to maintain an efficient voiding after surgical correction of the urinary incontinence.

Material And Methods: This was a cohort study of the urodynamic variables, mechanical work and energy of the detrusor, during cystometric and pressure-flow analysis, before and after antiincontinence surgery. Forty-five patients were included with urodynamic study before surgery and another one between 6 weeks and 6 months. We analyzed these data using student T test and ANOVA.

Results: The average and maximum flow rates, voiding efficient and velocity of the detrusor decreased. The pressures of the detrusor, the opening power and energy increased significantly after the surgery. These changes were more important in the Burch group. The 24.4% of the patients presented de novo hyperactive bladder; before surgery these patients had detrusor's pressures, voiding power and energy significantly greater.

Conclusion: There are changes in the mechanical properties of the detrusor after antiincontinence surgery; the detrusor needs a greater energy output to defeat urethral resistance and to maintain the vesical voiding, these were better in patients with Burch procedure and with overactive bladder.