Urethral pressure measurement by microtransducer: the results in symptom-free women and in those with genuine stress incontinence.

Urethral pressure measurements were recorded at rest and during stress by a microtransducer technique in 20 women without urinary symptoms and 120 women with urodynamically proven genuine stress incontinence. In the symptom-free women the resting profile values were largely maintained during stress, as a consequence of 100% transmission of intra-abdominal pressure rises to the proximal three-quarters of the functional urethral length. Whilst the majority maintained continence at the bladder neck level, 25% of these controls showed evidence of bladder neck opening during stress. The stress-incontinent patients showed a deficiency of pressure transmission ratios which appeared to have an 'all or none' character in the determination of symptoms. The amplitude and stability of the maximum urethral closure pressure at rest, the extent of urethral closure pressure lost in response to stress, and the extent of intrabdominal pressure rises interact to determine the severity of symptoms or 'margin to continence'.