Prevalence and significance of urethral instability in women with detrusor instability.

The phenomenon of urethral instability has been poorly defined and its significance is disputed. The aim of this study was to investigate the prevalence and significance of urethral instability in a group of women with idiopathic detrusor instability. Urethral instability was defined as a spontaneous fall in maximum urethral pressure of one-third or more, in the absence of detrusor activity, over a 2-min period. Urethral instability occurred in 42% of patients with detrusor instability and was strongly associated with the sequence of relaxation of the urethra prior to unprovoked detrusor contraction. Women with detrusor instability and a stable urethra exhibited primary contraction of the detrusor. The symptom of stress incontinence was more common in women with urethral instability. Women with detrusor instability may be subdivided into 2 groups on the basis of urethral instability, the presence of which suggests a primary dysfunction of the urethra. Such patients may derive more benefit from treatment with an alpha adrenoceptor agonist in addition to (or instead of) standard anticholinergic therapy.