The pressure-volume plot and prediction of treatment outcome in female incontinence.

A graphic representation of the micturition cycle by a pressure-volume plot has been obtained in 120 women, both incontinent patients and normal controls. The pattern of contraction during voiding allowed prediction of the outcome of treatment. Patients with urethral sphincter incompetence and a sustained detrusor contraction had a good result from colposuspension even if detrusor instability was found during filling. Where the urethral sphincter was competent, patients with urge incontinence with or without detrusor instability during filling cystometry had a good response to drugs, providing a sustained detrusor contraction was present during voiding. Urethral sphincter incompetence was characterised by a low detrusor voiding pressure.