Urgency: the cornerstone symptom of overactive bladder.

Urgency, defined as the compelling feeling of impending incontinence that is difficult to defer, is the cornerstone symptom of overactive bladder. Unfortunately, controversy continues to surround this term and its definition, a fact that has constrained the performance of clinical research in this field. It is important to note that the definition assumes an abnormal sensation that is distinguishable from the normal feeling of "urge to void," which occurs during a normal bladder-filling cycle. The cause of urgency is not fully understood and may vary from patient to patient. Urgency may be controlled by central nervous system mechanisms, lower urinary tract mechanisms, including detrusor myogenic functions (ie, overt detrusor contractions, micromotions, myofibroblast abnormalities), or afferent neural factors. Recently, a number of articles that attempt to quantify urgency have appeared in the literature. Attempts to measure urgency are confounded by difficulties in understanding its definition, the context of normal urge to void, and the power of suggestion in most clinical environments.