Pathophysiology of urinary incontinence

Urinary incontinence is highly prevalent, causes significant bother and has an immense social impact adversely affecting quality of life, productivity and relationships. Millions of individuals worldwide are affected, the vast majority being women. Stress, urgency and mixed urinary incontinence are the most common types, although other types of incontinence also occur. Stress incontinence occurs as a consequence of deficiency in the continence-maintaining mechanisms and urgency incontinence due to inappropriate activity of the bladder (detrusor) muscle, both being a failure of the storage function of the lower urinary tract. The pathophysiological mechanisms that underlie the various types of incontinence have long been contested and still remain the subject of much research. In this article we will review the most current theories for the development of incontinence with emphasis on the two commonest types of incontinence (stress and urgency). To fully understand the causal mechanisms it is vital that the normal function and innervation of the lower urinary tract is appreciated and this is also covered at the outset of this review.