OAB is a clinical diagnosis and comprises the symptoms of frequency (>8 micturitions / 24 hours), urgency and urge incontinence, occurring either singly or in combination, which cannot be explained by metabolic (e.g diabetes) or local pathological factors (e.g urinary tract infections, stones, interstitial cystitis).
In clinical practice, the empirical diagnosis is often used as the basis for initial management after assessing the individual’s lower urinary tract symptoms, physical findings and the results of urinalysis, and other indicated investigations. Thus, the International Continence Society in its Standardisation of Terminology report from 2002 defined the OAB syndrome as urgency with or without urge incontinence, usually with frequency and noctuira. These symptom combinations are suggestive of urodynamically demonstrable detrusor overactivity, but can be due to other forms of urethro – vesical dysfunction. The term “overactive bladder” can be used if there is no proven infection or other obvious pathology.
In the current International Continence Society (ICS) definition of the OAB syndrome, urgency is an obligatory component. This is in line with current opinion regarding the importance of urgency as the driving force behind the other components, frequency, nocturia and incontinence, which are also mentioned in the definition. Urgency is, however, difficult to measure and in many of the clinical trials assessing the pharmacological treatment of OAB syndrome, micturition frequency has often been used as the primary endpoint as it is easier to quantify.