Comparison of tension-free vaginal taping versus modified Burch colposuspension on urethral obstruction: a randomized controlled trial.

Objective: To determine whether the tension-free vaginal tape (TVT) procedure affects the mechanics of voiding in women with genuine stress incontinence (GSI).

Methods: Between July of 1997 and July of 1999, 116 women with GSI in the absence of pelvic prolapse underwent a randomized controlled study of TVT vs. modified Burch colposuspension. The trial was conducted by using a standardized protocol, including strict criteria for excluding preexisting bladder outlet obstruction (BOO). Urodynamic studies including free flowmetry, filling (provocative) and voiding cystometry, and 1-hour pad test were performed before and at least 1 year after the operation. The Blaivas and Groutz nomogram was used as another criteria to assess the pre- and postoperative BOO.

Results: Eighteen women were excluded from the study as a result of having preexisting BOO and an additional 8 were lost to follow-up. The comparison between pre- and postoperative variables for each procedure revealed that maximal flow rate of noninvasive uroflowmetry was significantly lower after operation in both groups (P = 0.009, P = 0.010, respectively). Detrusor pressure at maximal flow and urethral resistance were significantly higher and micturition volumes significantly lower after operation in the Burch group (P < 0.001, P < 0.001, P = 0.029, respectively). The difference between pre- and postoperative distribution of the obstruction nomogram of the Burch group was significantly different (P = 0.023).

Conclusions: Based on strict exclusion criteria for preoperative BOO, our findings strongly suggest that with a median 22 months (range, 12 to 36 months) of follow-up, a properly performed tension-free vaginal tape procedure does not cause urethral obstruction.