Abnormal urethral motor function is common in female stress, mixed, and urge incontinence.

AIM: To investigate the urethral motor function in incontinent women.

MATERIALS AND

METHODS

The intraurethral pressure was measured continuously in the high-pressure zone of the urethra at rest and during repeated short squeezes around the microtip transducer catheter in a group of 205 women with clinically manifest urinary incontinence (severe), and compared with the findings of investigations in 87 middle-aged women (53-63 years) with treatment naïve incontinence (mild-to-moderate) and healthy controls.

RESULTS

Women with established incontinence significantly (P < 0.001) more often (66%) had a pressure fall during or immediately following squeeze than women with treatment naïve incontinence (35%) or asymptomatic women (25%). The acceleration of urinary flow and the maximal flow rate were significantly (P < 0.01) increased in patients with incontinence: acceleration was 13 +/- 2.2 (17.8), 20 +/- 2.8 (18.9), and 32 +/- 4.9 (24.9) degrees (mean +/- SEM; SD) for incontinence, naïve incontinence and no incontinence, respectively; maximum urinary flow rate was 23, 22, and 16 ml/sec. No statistical differences in any of these measures were seen when stress and urge incontinence were compared.

CONCLUSION

Women with stress, urge, and mixed urinary incontinence seem to have a primary neuromuscular disorder in the urethra, which presents itself as an overactive opening mechanism with a urethral pressure fall instead of a pressure increase on provocation during the filling phase of the bladder, and during bladder emptying a more efficient opening of the bladder outlet than in normal women. We suggest that one and the same pathophysiological mechanism participates in female stress, urge, and mixed incontinence.