Overactive bladder or OAB refers to the feeling of needing to urinate much more often than the average person. Since the medical name for the bladder muscle is detrusor, you may hear this condition called names like “detrusor over-activity” or “detrusor instability”.
OAB is a complex problem, but generally occurs when abnormal messages are sent from the brain to the bladder muscle to squeeze too much or too soon. The bladder may squeeze hard enough to make urine leak out before you can make it to a restroom. This type of urine loss is called “urge incontinence”. OAB can occur at any age. Some people are born with conditions that affect nerve and muscle signals resulting in frequent urination, accidents and bed wetting in children. Other people may not develop OAB until they are older. The body and its muscles change with aging, making OAB quite common in the elderly.
In most adults, the bladder fills gradually over 3-5 hours and hold 300- 500cc of urine comfortably. When the bladder is full, sensory nerves send a fullness message to the brain and the pelvic muscles continue to squeeze and hold the urine in until a person is conveniently seated on the toilet. Then the bladder muscle contracts to empty, while the pelvic muscles relax to let urine pass through. Most people feel an urge to urinate when they hear running water or see a toilet, but can control the urge without leaking.