The Effect of Changes of Posture on the Urethral Closure Pressure in Stress-Incontinent Women

Abstract

The effects of changes of posture on intravesical and intra-urethral pressures were investigated in 10 women suffering from urinary stress incontinence. The patients were investigated in the supine and erect positions by simultaneous urethrocystometry and recording of the urethral pressure profile. In the supine position, the mean intravesical pressure was 12 mmHg, the mean maximum intra-urethral pressure 35 mmHg, and the mean urethral closure pressure 23 mmHg. When changing to the standing position, there was a statistically significant increase in the bladder pressure to 26 mmHg, and in the maximum intra-urethral pressure to 47 mmHg. The urethral closure pressure fell to 21 mmHg. The absolute length of the urethra increased from 25 to 30 mm, and the functional length from 20 to 22 mm. When compared with values found by the authors in an earlier, similar investigation on normal women, the maximum intra-urethral pressure is lower, and the functional and absolute lengths of the urethra are shorter in stress-incontinent women than in healthy females. On changing from the supine to the standing position, the maximum intravesical and intra-urethral pressures rise, but the increase in intra-urethral pressure is less than the increase in bladder pressure. This leads to a negative closure pressure and an impaired continence.