How Your Bladder Works

Continence depends on the normal functioning of the bladder, urethra, sphincters and pelvic floor muscles.

The position of the bladder

Your bladder is a hollow muscle, much like a balloon, located behind your pelvic bone and below your belly button. When full, the bladder can hold as much as half a litre of urine. The detrusor is a thick, smooth muscle in the wall of the bladder. It is relaxed and expands as the bladder fills with urine. It contracts and tightens to empty the bladder when you urinate.

At the neck of the bladder is the urethra, a thin tube that leads from the bladder to the outside of the body. In women the urethra is about 1.5 inches long and is located in front of the vagina. The opening of the urethra is called the meatus and is located between the clitoris and the vaginal opening.

Urine is stored in the bladder until it is passed through the urethra and out of the body. Two structures at the neck of the bladder, called sphincters, pinch the neck and keep urine in the bladder until you are ready to urinate.

The bladder neck and urethra are supported by the pelvic floor muscles. These muscles, which are shaped like a sling, attach to the spine in the back and the public bone in front, and keep your bladder, uterus and rectum in place. The position of these organs has a direct effect on the control of urine. Stretched and weakened pelvic floor muscles means these organs can shift and interfere with the functioning of your bladder.

Types of Incontinence

Urinary incontinence may be either transient (meaning it is temporary or reversible) or chronic (meaning it is long-term).

Transient Incontinence
Transient incontinence is usually related to an illness or a medical problem and disappears once the illness or problem is resolved. For example, urinary tract infections can cause bladder control problems. Certain medications, such as sedatives and diuretics, can also lead to urinary incontinence. If the incontinence experienced by a postmenopausal woman is caused by recurrent urinary tract infections, then taking a vaginal estrogen therapy may improve the symptoms associated with the incontinence.

Chronic Incontinence
Chronic incontinence is due to changes in the bladder and urethra or is the result of damaged pelvic muscles and nerves. Multiple pregnancies or aging can cause pelvic organs to shift and interfere with bladder function. Common types of chronic incontinence are:

• Stress incontinence
• Overactive bladder
• Mixed incontinence
• Overflow incontinence

Click here for descriptions of these common types of incontinence.