A brief physiology and pathophysiology of the bladder

The remit of this review is confined to experimental works and publications relevant to the integral theory of female urinary incontinence (IT). Since its first publication in 1990, the IT has challenged the general view that the pathogenesis of overactive bladder (OAB) (urge, frequency, nocturia) is unknown and there is no cure. According to the IT, normal function bladder control is binary, either closed or open. Control is cortical via a peripheral feedback component: oppositely acting reflex striated pelvic muscles contract against suspensory ligaments to close the urethra for continence, open it prior to evacuation, and stretch the vagina like a trampoline to prevent excess impulses from the urothelial stretch receptors which may cause unwanted urgency at low bladder volumes (OAB). The pathogenesis of female urinary incontinence is from outside the bladder, mainly weak ligaments or vagina, due to collagen deficiency. Damage in childbirth (collagen depolymerization) and age (collagen loss) make ligaments vulnerable to damage. With weak ligaments, muscles contracting against them weaken: the muscles cannot close the urethra (manifested as stress incontinence), open it (manifested as emptying problems or retention) or stretch the vagina to prevent the urothelial stretch receptors firing off prematurely (manifested as urge incontinence). Weak pubourethral ligaments can cause stress urinary incontinence (SUI), or SUI plus urge (mixed incontinence). Weak uterosacral ligaments (USLs) can cause urge, frequency, nocturia and emptying difficulties. Treatment consisting of surgical/non-surgical strengthening of ligaments can cure or improve SUI, OAB, and emptying dysfunctions. In summary, bladder control is from outside the bladder, binary, with cortical and peripheral components. A small change in definition, from "overactive" to "overactivated" is consistent with this concept, retains the acronym "OAB", and opens the door to probability of cure and a massive increase in research endeavours.