Why do women have voiding dysfunction and de novo detrusor instability after colposuspension?

Objective To investigate the causes of voiding dysfunction and new detrusor instability after colposuspension. Design Prospective, observational study. Setting Urogynaecology unit, district general hospital. Population Seventy-seven women undergoing colposuspension for genuine stress incontinence. Methods The following factors were investigated: 1. bladder neck elevation by magnetic resonance imaging before and after surgery; 2. urethral compression by measuring bladder neck approximation to the pubis with magnetic resonance imaging after surgery (anterior compression) and the distance between the medial stitches during surgery (lateral compression); 3. clinical and urodynamic factors. Main outcome measures 1. Post-operative voiding function (i.e. first day of voiding and day of catheter removal); 2. objective evidence of detrusor instability three months post-operatively. Results Pre-operative peak flow rate (P = 0.004), straining during voiding (P = 0.005), increasing age (P < 0.001), operative elevation (P < 0.001) and anterior urethral compression (P = 0.001) were associated with the number of days of post-operative catheterisation. Increasing age (P = 0.02), previous bladder neck surgery (P = 0.04), operative elevation (P = 0.049) and anterior urethral compression (P < 0.001) were associated with detrusor instability at three months. Conclusion Surgical factors (bladder neck elevation and compression) are associated with voiding dysfunction and detrusor instability after colposuspension. These findings have implications for prevention.