In order to understand the possible causes of urinary incontinence it is important to understand the many processes that work together in the normal process of urination.
Urine is produced by the kidneys and passes into a muscular sac called the urinary bladder. The urethra is the tube that leads from the bladder to the outside of the body.
A ring of muscles, called the urinary sphincter, surrounds the urethra. As the bladder fills with urine, the sphincter muscles are contracted and the bladder muscle stays relaxed. This allows the bladder to fill with urine and prevents urine from leaking out.
When the bladder is nearing full, nerve signals are sent to the brain, letting the person know that the bladder is getting full. Additional nerve signals are sent out to begin urination. Some of these signals cause the bladder muscles to contract, which pushes urine into the urethra. At the same time, other signals cause the sphincter muscles to relax, which allows the urine to pass out of the body. Most people empty their bladder every three to five hours during the day and zero to one times during the night.
Now that we reviewed the normal process, it is easier to understand where things can go wrong.
Urge Incontinence - In this type of incontinence, the bladder contracts before the person is ready to urinate. This is the most common type of incontinence.
Stress Incontinence - In this type of incontinence, the sphincter does not close properly or does not stay closed when there is increased pressure (as with a cough or sneeze), allowing urine to leak. This is an especially common cause of incontinence in women, especially women who have had children.
Overflow Incontinence - If the bladder is too weak to empty completely, this can cause leakage when bladder is overly full. This is a rare type of incontinence.
Obstruction - If the urethra is obstructed, this can prevent urine from draining completely, which can also lead to overflow incontinence. This is common in men with an enlarged prostate.
Medical or other conditions - Urine leakage also can occur when a person is unable to make it to the toilet on time as a result of medical conditions, medications, and/or difficulty with thinking clearly.
