The unstable urethra in the female.

The clinical and urodynamic characteristics of 54 women with unstable urethras (falls of urethral pressures of at least 20 cm H2O) were compared with those of 171 patients with stable urethras. The unstable-urethra patients were younger and presented with an increased incidence of marked urgency and a lower incidence of genuine stress incontinence. The average urethral pressure fall was preceded by a 6-cm increase in maximum urethral pressure. The mean (+/- SD) fall of urethral pressure was 30 +/- 12 cm H2O and the average duration of the event was 8 seconds. The level of the urethral pressure fall was not influenced by bladder volume but correlated positively with higher maximum urethral pressures. The present findings suggest that the unstable urethra plays a limited role in genuine stress incontinence but may be linked with the unstable detrusor.

Diagnosis of the unstable detrusor: comparison of an incremental and continuous infusion technique.

Incremental infusion cystometry and continuous infusion urethrocystometry were performed on sequential days in 52 patients with an unstable detrusor. Bladder compliance was the same in both techniques. However, continuous infusion urethrocystometry demonstrated involuntary detrusor contractions in three times as many patients as incremental infusion cystometry. It is concluded that in the supine position, medium rate continuous infusion urethrocystometry is more discriminating than rapid rate incremental infusion cystometry with a Lewis recording cystometer in the demonstration of involuntary detrusor contractions.