INTRODUCTION — Urinary incontinence is the involuntary leakage of urine. Although it becomes more common as people get older, incontinence is not normal at any age. Many types of therapy are available for urinary incontinence. A brief review of the normal process of urination in adults will help in understanding both the causes and treatment of urinary incontinence.

NORMAL 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 (show figure 1).

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.

Simply put, four things can go wrong with this process:

• The bladder contracts when the person is not ready to urinate, called urge incontinence. This is the most common reason people have 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 called stress incontinence, and is a common reason for incontinence in women, especially women who have had children.

• The bladder is too weak to empty completely, causing leakage when the bladder is overly full. This is called overflow incontinence, and is uncommon.

• The urethra is obstructed, preventing urine from draining completely, which can also lead to overflow incontinence. This is common in men with an enlarged prostate.

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.

RISK FACTORS — The frequency of urinary incontinence increases with age, and it affects more women than men. About 10 to 30 percent of women and 1.5 to 5 percent of men up to age 64 have urinary incontinence. In those age 65 and older, 15 to 30 percent of people have incontinence. At least 50 percent of people older than 65 who live in long-term care facilities (eg, nursing homes) have incontinence [1].

Urinary incontinence also has been associated with a number of conditions, including obesity (in women), high impact physical activities, heart failure, lung problems, smoking, chronic cough, depression, constipation, pregnancy, vaginal delivery, and problems with mobility.

TYPES OF URINARY INCONTINENCE

Urge incontinence — Urge incontinence occurs when the bladder contracts suddenly, so that a normal "urge" becomes more forceful "urgency", the strong, uncomfortable need to urinate. A person with urge incontinence will generally have an abrupt, overwhelming urge to urinate, followed by urine leakage that can range from a few drops to soaking. The urgency and leakage may occur in response to a stimulus, such as unlocking the door when returning home, going out in the cold, turning on the faucet, or washing the hands.

There are many names that have been used for urge incontinence and the associated symptoms of urgency and frequency, including overactive bladder, detrusor instability or overactivity, and irritable or spastic bladder.

Some people with overactive bladder have symptoms of urinary urgency and frequency during the daytime only, while other people also have to urinate frequently during the night (called nocturia). Frequency is defined as the need to urinate more often than other people (normal is considered to be eight times in 24 hours).

Factors that can lead to urge incontinence include age-related changes in the urinary tract, nervous system problems related to a medical problems such as stroke, or bladder irritation caused by inflammation.

Stress incontinence — Stress incontinence occurs when the urinary sphincter does not stay closed when there is an increase in pressure in the abdomen, leading to urine leakage. As an example, coughing, sneezing, laughing, or running can cause episodes of stress incontinence. Stress incontinence is the most common cause of urinary incontinence in younger women, the second most common cause in older women, and may occur in older men after certain types of prostate surgery.

Stress incontinence in women is most commonly caused by weakness in the muscles and other tissues that support the urethra. Less commonly, stress incontinence is caused by complete failure of the sphincter to close, a condition known as intrinsic sphincter deficiency (ISD). This can occur as a result of scarring from surgery or radiation therapy used for cancer treatment.

Mixed incontinence — Mixed incontinence is the combination of both urge and stress incontinence, and is most common in younger to middle aged women.

Incontinence associated with medical conditions — Urinary incontinence can occur as a result of treatable factors or medical conditions (show table 1A-1B). As examples, medical conditions such as urinary tract infection or poorly-controlled diabetes may temporarily cause urinary leakage. Certain medications, excess fluid intake, fluid retention, and arthritis or other problems that cause difficulty with mobility are potentially treatable causes of incontinence.

Overflow incontinence — Overflow incontinence refers to leakage that occurs when the bladder fails to empty properly, either because of obstruction of the urethra or weak bladder muscle contractions. Abnormally large amounts of urine remain in the bladder, even after the person tries to empty. The person may also notice a weak stream, dribbling, or needing to go frequently.

Overflow incontinence is relatively uncommon, but can occur in some older men in whom either benign or cancerous enlargement of the prostate (a gland that surrounds the urethra) causes marked narrowing of the urethra. It is uncommon in women.

DIAGNOSIS — One of the most important first steps in the diagnosis and treatment of urinary incontinence is to openly and honestly discuss the problem with a healthcare provider. Studies have shown that up to one-half of people with incontinence do not discuss their problem with a healthcare professional. However, disclosing the problem can help to get an accurate diagnosis and effective treatment.

A number of tools are available to help determine the cause of urinary incontinence.

History and physical examination — The history and physical examination are among the most important steps in the investigation and treatment of urinary incontinence. Important questions to discuss include:

• When does leakage occur? (ie, is it associated with urgency, coughing/sneezing, or does it occur without warning?)
• When did your leakage begin? Has it worsened or improved over time?
• Have you tried any treatments to reduce leakage?
• If there is any leakage of stool (fecal incontinence)?

Bladder diary — A bladder diary is a record of the amount of urine voided, frequency and amount of leakage, amount of fluid consumed, and any associated factors that cause leakage, such as coughing or sneezing (show figure 2A-2B). This provides useful information about the cause(s) and potential treatment of incontinence.

Office tests — Simple tests may be done during an office visit to determine the type of leakage a person is experiencing. This may include a cough test, when the patient is asked to cough several times while the provider watches for urine leakage. Other possible tests include measurement of the post void residual, which is the amount of urine left in the bladder after urinating. This can be done with an ultrasound probe (called a bladder scan) or by inserting a catheter into the bladder.

Laboratory tests — A urine test (urinalysis) is usually done to look for evidence of infection or blood in the urine. Blood tests may be ordered to measure the kidney function.

Urodynamic testing — During a urodynamic test, a small catheter is inserted into the bladder and the rectum or vagina. The bladder is slowly filled with water testing examines the bladder, urethra, and urethral sphincter as the bladder is filled with water, when the bladder is full, and when the person coughs or bears down. Testing includes measurement of the bladder capacity (how much the bladder can hold), the pressures in the bladder and urethra, and how fast urine flows during urination.

Urodynamic testing is not needed for everyone with incontinence, but may be recommended in certain situations, such as to confirm stress incontinence if surgery is planned.

TREATMENT — The treatment options for urinary incontinence are discussed in a separate topic review. (See "Patient information: Urinary incontinence treatments").

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.