[Decreased urethral pressure after coughing: the concept of urethral fatigability. Its relationship with active forces of continence].

The existence of urethral fatiguability was demonstrated by a sphinctometric study in 30 women. Comparison of the baseline urethral pressure values and after 6 maximal coughs demonstrated a mean reduction in urethral pressure of 40% (range: 24.5 to 90%) in 10 out of 18 women with stress incontinence. This decreased pressure lasted for several seconds. Spectral analysis of the electromyographic recording of the striated urethral sphincter under basal conditions and then after coughing confirmed the intervention of the striated and periurethral musculature with a marked quantitative decrease in the electrical activity of the sphincter. The clinical pathophysiological, prognostic and therapeutic implications of this new concept are discussed.