Altered voiding after the tension-free vaginal tape procedure: is increased resistance the mechanism of therapy?

Abstract

Objective: Tension–free vaginal tape (TVT) is gaining popularity as an effective treatment for genuine stress urinary incontinence. To better understand the procedure’s mechanism, we prospectively assessed voiding indices in a cohort of patients undergoing TVT for stress incontinence. Methods: We compared the preoperative and postoperative pressure flow studies of women who underwent TVT between November 1998 and July 1999. From the maximal flow rate (Qmax) and detrusor pressure at maximal flow rate (Pdet), the urethral resistance (R = P/Q²) was calculated. Results were compared using one-tailed t test for paired values. Results: At a mean follow-up of 4 months, 10 of 18 women undergoing TVT had adequate voiding studies. All were both subjectively and objectively cured of their stress incontinence. Both mean detrusor pressure and mean urethral resistance increased significantly postoperatively. Cotton swab tests results for hypermobility remained positive postoperatively in 9 of 10 patients. Conclusions: Urethral resistance during voiding increases when TVT corrects stress incontinence. A surgical procedure may correct stress incontinence without affecting proximal urethral mobility.