Urinary incontinence is loss of control of the bladder, a balloon-like organ that stores urine. It is a symptom, not a disease in itself, and can indicate some underlying medical condition.

Incontinence is a problem of the urinary system, which involves the kidneys, ureters, bladder and urethra. The kidneys are two bean-shaped organs that remove waste and water from the blood to produce urine. The muscular, tube-like ureters move urine from the kidneys to the bladder. Urine is stored in the bladder until it flows out of the body through a tube connected to the bottom of the bladder called the urethra.

A ring of muscles called the urinary sphincter surrounds the urethra. As the bladder fills with urine, a complex system of coordinating nerve signals make the sphincter muscles contract, which close off the opening to the bladder while at the same time, the bladder muscles relax. This action prevents urine from leaking out of the body.

When the bladder fills to a certain level, nerve signals are sent to the brain, giving it the sensation that the bladder is getting full. Additional nerve signals must be sent in a coordinated fashion to initiate urination. Some of these signals make the bladder muscles contract, pushing urine into the urethra. Other signals make the sphincter muscles relax, allowing urine to exit the body.

Urinary incontinence occurs when:

• The bladder contracts when it should not
  
  
• The bladder fails to contract properly, leading to a buildup of urine in the bladder and subsequent leakage
  
  
• The sphincter does not close properly or does not remain closed when subjected to pressure, allowing urine to leak
  
  
• The urethra is obstructed, preventing proper drainage of urine

According to the National Institutes of Health, 20 million women and 6 million men are currently living with or deal with incontinence at some point in their lives. Approximately 20 percent of women younger than 45 years have problems with bladder control. This increases to almost 30 percent of women aged 80 years or older. Incontinence rates among men rise from 5 percent of those younger than 45 years to more than 20 percent of the 65 years and older age group. It is important to note that, although it is more common in older adults, incontinence is not considered a normal part of the aging process.

Urinary incontinence can be caused by a number of factors, but is best known for its association with a condition called overactive bladder (OAB). OAB is caused by involuntary bladder contractions that occur as the bladder fills. Only one type of incontinence is associated with OAB – urge incontinence (an urgent need to pass urine).