Urinary incontinence is an inability to hold your urine until you get to a toilet. Women experience incontinence twice as often as men, due to factors such as pregnancy and childbirth, menopause, and the structure of the female urinary tract. Older women experience incontinence more often than younger women, but incontinence is not inevitable with age.

The body stores urine—water and wastes removed by the kidneys—in the bladder, a balloon-like organ. The bladder connects to the urethra, the tube through which urine leaves the body. During urination, muscles in the wall of the bladder contract, forcing urine out of the bladder and into the urethra. At the same time, sphincter muscles surrounding the urethra relax, letting urine pass out of the body.

Two structures that help keep urine in the bladder are the pelvic floor muscles and the urethral sphincter.

The pelvic floor muscles support the vagina, urethra and other organs in the pelvis. When the pelvic floor muscles are strong, the urethra and bladder cannot move out of place. This helps keep the urethra closed, so urine cannot leak from the bladder.

The urethral sphincter is a band of muscles around the urethra. When these muscles are strong, they squeeze tightly and keep urine in the bladder. When you want to urinate you can relax these muscles.

Incontinence in women usually occurs because of problems with pelvic floor muscles—which can be damaged during childbirth—or problems with the urethral sphincter.

Stress incontinence and urge incontinence are the two most common types of incontinence in women. When these two conditions occur together, doctors may use the term "mixed incontinence."

Stress Incontinence—If coughing, laughing, sneezing, or other movements that put pressure on the bladder cause you to leak urine, you may have stress incontinence. Physical changes resulting from pregnancy, childbirth, and menopause often cause stress incontinence. It is the most common form of incontinence in women and is treatable. Urge Incontinence—If you lose urine for no apparent reason while suddenly feeling the need or urge to urinate, you may have urge incontinence. The most common cause of urge incontinence is inappropriate bladder contractions.

If you experience urinary incontinence, the important thing to know is that incontinence is treatable and often curable at all ages. So even though you may feel embarrassed, discuss the problems you are having with your doctor.²

2. NIH Publication No. 04-4132. September 2004
Available at: http://kidney.niddk.nih.gov/kudiseases/pubs/uiwomen