Overactive bladder symptoms: do we need urodynamics?

The aim of our study was to determine whether the urodynamic diagnosis is useful in the management of women with symptoms of an overactive bladder (OAB).

Women with lower urinary tract symptoms, attending a tertiary referral urogynaecology clinic were studied. All women were fully evaluated, with history, urinary symptoms questionnaire, frequency-volume chart, vaginal examination, and videocystourethrography. Women with symptoms consistent with an overactive bladder (urinary frequency, urgency, and/or urge incontinence) were selected. Women with neurological disorders were excluded. Finally, urinary symptoms and urodynamic diagnosis were correlated. All terms and definitions are in accordance with the International Continence Society [Abrams et al., 1988, Scand J Urol Nephrol 114(Suppl):5-19.].

A total of 4,500 women 22-73 years of age were studied. Only 843 women (18.7%) could be classified as having an OAB. Of these, 457 women (54.2%) had urodynamically proven detrusor instability, whereas 386 women (45.8%) had a stable urodynamic trace. Sixty-eight (8.1%) of the women studied had postvoid residual greater than 100 mL. Of the 4,500 women studied, 1,641 (36.5%) had detrusor instability on laboratory urodynamics. Only 27.5% of these women (457 of 1,641) had OAB symptoms.

Symptomatic diagnosis of OAB does not correlate with a urodynamic diagnosis of detrusor instability. The diagnosis of overactive bladder based on urinary symptoms underdiagnoses the condition of detrusor instability in a population of women suffering from lower urinary tract symptoms. Therefore, symptomatic diagnosis of OAB alone is not recommended. Our study suggested that urodynamic evaluation is mandatory in the management of the women with symptoms of an overactive bladder.