[A new approach to urinary continence disorders in women: urodynamic ultrasonic examination by the vaginal route]

Abstract

The vesicourethral junction, the urethra cannot be seen when using the abdominal approach because of the interposition of the pubic symphysis. The ultrasonic vaginal approach makes it possible. 53 patients were ultrasonically observed during an urodynamic exploration. The simultaneous utilization of both methods has permit to observe the mechanisms of normal or pathological voiding. When initiating a voluntary micturition, an area (called "prepubic muscle") located in front of the pubic symphysis between the clitoris and the urethral meatus, exert a traction on the periurethral sphincteric area. This sphincteric area, which is well shown by ultrasound, contracts longitudinally (causing shortening of the urethra and opening of the bladder neck) and causes a drop in urethral closure pressure. The increase in the distance between the inferior part of the pubic symphysis and the anterior vaginal wall comes about because of slackening of the elevator ani muscles. This slackening occurs at different times before the bladder contracts. The urethra opens; the complete course of this organ is well defined. Things return to their previous state when voiding finishes. In the case of stress incontinence, the lack of transmission of pressure urodynamically found when the woman is coughing can be seen as a sliding mechanism within the space of Retzius and at the urethro-vesical junction behind the symphysis pubis. The degree of sliding depends on the strength of the cough. In all cases of pure stress incontinence without there being low urethral closure pressure, a maximum stress caused by coughing will produce more than 5 MM sliding before the urethra opens. If the urinary incontinence is due to low urethral closure pressure, the urethra opens without sliding of the urethro-vesical junction whenever the abdominal pressure increases. Urethral instability resembles voluntary voiding but without any voluntary command. "Prepubic" contractions, longitudinal contractions in the sphincteric area and slackening of the levator ani muscles, alone or in association, explain why urethral closure pressure drops. Sometimes this drop is followed by an increase in bladder pressure.