[Physics of materials and female stress urinary continence: New concepts: I) Elasticity under bladder].

OBJECTIVE

Improving the understanding of the adaptation to stress of urinary continence.

METHODS

A transversal analysis between physics of materials and the female anatomy. Laws of physics of the materials and of their viscoelastic behavior are applied to the anatomy of the anterior vaginal wall.

RESULTS

The anterior vaginal wall may be divided into two segments of different viscoelastic behavior, the vertical segment below the urethra and the horizontal segment below the bladder. If the urethra gets crushed on the first segment according to the hammock theory, the crushing of the bladder on the second segment is, on the other hand, damped by its important elasticity. The importance of this elasticity evokes an unknown function: damping under the bladder that moderates and delays the increase of intravesical pressure. This damping function below the bladder is increased in the cystocele, which is therefore a continence factor; on the other hand, it is impaired in obesity, which is therefore a factor of SUI.

CONCLUSIONS

It is necessary to include in the theory of stress continence, the notion of a damping function below the bladder.