Voluntary contractions in the female urethra.

The continence mechanism of the female urethra has been investigated by a method that makes possible simultaneous recording of an induced intraurethral pressure and the related cross-sectional area. Muscular work, power and velocity of contraction could be calculated on the basis of these recordings at rest and during voluntary contractions of the pelvic floor. With these parameters it was possible to demonstrate 2 different components in the continence function: one in the mid urethra that maintains the closure pressure at rest and another more proximally in the urethra that is capable of fast, powerful contractions.