Mechanical properties of the urethra in healthy and stress incontinent females: dynamic measurements in the resting urethra.

The relationship between pressure and cross-sectional area in the resting urethra during its inflation and deflation was examined in 30 healthy females and in 30 patients with genuine stress incontinence (GSI). Measurements were performed at the bladder neck, in the high-pressure zone and distally in the urethra. The mechanical properties of the urethra were found to vary significantly as a function of time after induction of a cross-sectional area (stress episode) in both groups of women. The pattern of response of the urethra showed significant differences between normals and GSI particularly during dynamic conditions. Our results indicate that mechanical laxity of the urethra at the bladder neck and midurethrally especially at dynamic events (stress episodes) is of pathophysiological importance in GSI.