Incontinence Causes

There are many possible causes of urinary incontinence, and sometimes there are several causes occurring at the same time. Diagnosis and therapy are more difficult when more than one cause is present, but the cause or causes of incontinence must be identified to provide effective treatment.

Stress Incontinence

Stress incontinence occurs during physical activity; urine leaks out of the body when the stomach muscles contract (for example, when sneezing, laughing, or even standing up from a seated position). Stress incontinence is most commonly caused when the urethra (the tube from the bladder to the outside of the body) is hypermobile because of problems with the muscles of the pelvis. A less common cause of stress incontinence is a muscle defect in the urethra known as intrinsic sphincter deficiency. The sphincter is a muscle that closes off the urethra and prevents urine from leaving the bladder and passing through the urethra to the outside of the body. If this muscle is damaged or deficient, urine can leak out of the bladder. Obviously, some people may have both.

Stress incontinence is the most common type of bladder control problem in younger and middle-aged women. In some cases, it is related to childbirth. It may also begin around the time of menopause. Stress incontinence affects 15-60% of women and can affect young and older people. It is especially common in young female athletes who have never given birth, and it occurs while they are participating in sports.

Urge Incontinence

People with urge incontinence cannot hold their urine long enough to get to the toilet in time; it is also called overactive bladder. Healthy people can have urge incontinence, but it is often found in people who have diabetes, stroke, Alzheimer disease, Parkinson disease, or multiple sclerosis.

Urge incontinence occurs due overactivity of the bladder wall muscle (the detrusor). Urge incontinence may be caused by a problem with the muscle, with the nerves that control the muscle, or both. If the cause is unknown, it is called idiopathic urge incontinence. Overactive bladder, or urge incontinence, without neurologic causes is called detrusor instability, meaning the muscle itself contracts inappropriately.

Mixed Incontinence

Mixed incontinence is caused by a combination of stress and urge incontinence. In mixed incontinence, the muscle controlling the outflow of the bladder (the sphincter) is weak, and the detrusor muscle is overactive. A common combination involves a hypermobile urethra and detrusor instability.

Reflex Incontinence

Reflex incontinence is caused by a problem in the central nervous system (the brain and spinal cord). Common disorders associated with reflex incontinence include stroke, Parkinson disease, and brain tumors. Reflex incontinence also occurs in patients with spinal cord injuries and multiple sclerosis.

Overflow Incontinence

Overflow incontinence occurs because the bladder fills too full and urine passively leaks or overflows through the urinary sphincter. This can occur if the flow of urine out of the bladder is constricted or blocked (bladder outlet obstruction), if the bladder muscle has no strength (detrusor atony), or if there are neurologic problems. Common causes of bladder outlet obstruction in men include benign prostatic hyperplasia (BPH or nonmalignant enlargement of the prostate gland), bladder (vesical) neck contracture (narrowing of the outlet from the bladder due to scarring or excess muscle tissue), and urethral narrowing (strictures). Bladder outlet obstruction can occur in women with significant pelvic organ prolapse (such as a prolapsed uterus). It may even occur after surgery to correct incontinence (such as the sling or bladder neck suspension procedures); this is called iatrogenically induced overflow incontinence.

Some common neurologic causes of overflow incontinence include herniated lumbar disc, diabetes-related bladder problems, and other nerve problems (peripheral neuropathy). Less common causes of overflow incontinence include AIDS, genital herpes affecting the area around the urethra (the perineal area), and neurosyphilis.

Functional Incontinence

This type of incontinence occurs when a person is unable to reach the toilet in time due to a physical or mental impairment. For example, a person with severe arthritis may not be able to unbutton his or her pants quickly. Someone with Alzheimer disease may not plan a trip to the bathroom.