Objective To compare elevation and movement of the bladder neck after tension-free vaginal tape and open Burch colposuspension, using transperineal ultrasound.

Design Prospective, non-randomised study using pre- and post-operative transperineal ultrasound of the bladder neck.

Setting Tertiary referral urogynaecology unit at a London teaching hospital.

Sample Thirty consecutive women who underwent tension-free vaginal tape or colposuspension for primary genuine stress incontinence between March 1998 and June 1999.

Methods Women underwent transperineal ultrasound of the bladder neck prior to and three to four weeks after surgery.

Main outcome measures Bladder neck elevation, angle and movement in relation to the pubic symphysis.

Results For both tension-free vaginal tape and colposuspension the post-operative bladder neck angles at rest and valsalva were more acute than pre-operatively. The post-operative linear movement on valsalva was less than pre-operatively. For colposuspension the rotational movement on valsalva was significantly less post-operatively, but for tension-free vaginal tape there was only a trend towards less post-operative rotational movement. Post-operative angles and movement were significantly less for colposuspension. The resting bladder neck position was elevated significantly more by colposuspension.

Conclusion Both tension-free vaginal tape and colposuspension decrease bladder neck angles at rest and valsalva, linear movement on valsalva and elevate the bladder neck. The colposuspension causes significantly more change than the tension-free vaginal tape. This suggests the mechanism of continence for the tension-free vaginal tape is less dependent on bladder neck change than the colposuspension.