Urodynamic norms in women. I. Normals versus stress incontinents.

Urodynamic statistics for normal women were compared to similar norms for stress incontinent women. It was concluded that 1) the reduction of flow rate in stress incontinent patients appears to be the result, with high probability of pathologic changes in the function of the distal urethra, 2) stress incontinence does not affect the combined effects of bladder pressure and the proximal urethral resistance during voiding as reflected in velocity, 3) the distal urethral cross-sectional area appears to be under neuromuscular control and 4) the distal urethra of stress incontinent women appears to be incapable of opening as widely as the distal urethra of normal women. It is not currently possible to assign anatomical or physiological causes to the observed phenomena.