Urgency: all or none phenomenon?

Urgency is the key symptom of a very prevalent symptom complex, the overactive bladder syndrome. Addressing urgency as a hallmark for detrusor overactivity is for physicians very comfortable, but appears to be an oversimplification of a very complex symptom entity. This overview tries to put the relevant literature on urgency against the question whether urgency is an all or none phenomenon, and summarizes the current views on how urgency is perceived.