Epidemiology, pathophysiology, and evaluation of urinary incontinence and overactive bladder.

OBJECTIVES: To present an overview of current knowledge regarding the epidemiology, pathophysiology, and evaluation of urinary incontinence (UI) with a focus on the problem of the overactive bladder.
METHODS: The most recent data on the epidemiology of UI are presented. The literature on the pathophysiology of urinary urge incontinence (UUI) is reviewed, and key concepts related to patient evaluation are summarized.
RESULTS: The prevalence of UI depends on the population being surveyed. The overactive bladder constitutes a substantial percentage of the overall problem, ranging from > 50% of incontinent men to only 10% to 15% of incontinent younger women. Few data are available on the incidence of the disorder or on racial/ethnic trends. Overactive bladder or urge incontinence is called detrusor hyperreflexia when a neurologic cause is known and detrusor instability when there is no neurologic abnormality. Although the pathophysiology of idiopathic instability is not well understood, some evidence suggests that this condition may result from subclinical neurologic disease or primary smooth muscle disease. Most patients with UUI can be adequately evaluated with a history, physical examination, determination of postvoid residual volume, and urinalysis. When neurologic disease or other complicating factors are present, or if initial treatment fails, sophisticated urodynamic testing is appropriate.
CONCLUSIONS: Urinary incontinence is prevalent in all strata of the population, although it affects women and the elderly disproportionately. With the exception of cases in which a neurologic lesion can be demonstrated, the etiology of UUI remains elusive. A thorough history, physical examination, determination of postvoid residual, and urinalysis will be adequate to classify and treat the majority of patients.