This is a sudden, intense urge to urinate, followed by an involuntary loss of urine. Even the smallest distance to the toilet is a problem for people with OAB. With urge incontinence, you may also need to urinate often. The need to urinate may even wake you up several times a night.
Some people with urge incontinence have a strong desire to urinate when they hear water running, as the psychological effect starts the chemical reaction in the body causing the messages to the brain signal to empty the bladder. Urge incontinence may be aggravated by a urinary tract infection or by anything that irritates the bladder. It can also be caused by bowel problems or damage to the nervous system associated with multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, stroke or injury.
Lets look at the mechanics and how a normal functioning bladder works differs from how an overactive bladder works.
Mechanism of a normal bladder
A healthy adult bladder is capable of holding around 500ml of urine. When the bladder starts to fill, the detrusor muscle inside the bladder stretches and receptors send a message to the brain via the spinal cord, the brain then sends a message back down the spinal column to the involuntary muscles in the pelvic area and urethra to automatically close and tighten keeping the urine inside the bladder until you command the brain to relax the muscles to urinate. Upon normal urination, the detrusor muscle would contract and as you relax the voluntary muscles the bladder is able void.
It’s a little bit more complex that, but this is a general overview for people who don’t understand the mechanics of the urinary system.
Mechanism of an overactive bladder
As the bladder starts to fill or even the sound of running water triggers off a premature contraction of the detrusor muscle. This contraction is signalled by the brain and hence the ‘urge’ to pass water is imminent. The bladder doesn’t need to be full at this stage, it could have as little as 150mls of urine inside before the detrusor muscle contracts. This contraction tells the brain the bladder is full when in fact it isn’t.