Overactive bladder occurs when abnormal nerves send signals to the bladder at the wrong time, causing its muscles to squeeze without warning. Voiding up to seven times a day is normal for many women, but women with overactive bladder may find that they must urinate even more frequently. Specifically, the symptoms of overactive bladder include:
Urinary frequency:
bothersome urination eight or more times a day or two or more times at night
Urinary urgency:
the sudden, strong need to urinate immediately
Urge incontinence:
leakage or gushing of urine that follows a sudden, strong urge
Nocturia:
awaking at night to urinate
Treatment for overactive bladder involves behavioral modifications and/or medications.
A person's ability to hold urine and maintain continence depends on normal function of the lower urinary tract, the kidneys, and the nervous system. The person must also have a physical and psychological ability to recognize and appropriately respond to the urge to urinate . The bladder's ability to fill and store urine requires a functional sphincter muscle (which controls the flow of urine out of the body) and a stable bladder wall muscle (detrusor).
The process of urination involves two phases:
- Filling and storage
- Emptying
During the filling and storage phase, the bladder stretches so it can hold the increasing amount of urine. The bladder of an average person can hold 350 mL to 550 mL of urine. Generally, a person feels like they need to urinate when approximately 200 mL of urine fills up in the bladder. The nervous system tells you that you need to urinate, and also allows the bladder to continue to fill.
The emptying phase requires that the detrusor muscle contract, forcing urine out of the bladder. The sphincter muscle must relax at the same time, so that urine can flow out of the body.
The bladder of an infant automatically contracts when a certain volume of urine is collected in the bladder. As the child grows older and learns to control urination, part of the brain (cerebral cortex) helps prevent bladder muscle contraction. This allows urination to be delayed until the person is ready to use the bathroom.
Undesired bladder muscle contractions may occur from neurological problems and bladder irritation.