causes of chronic urinary incontinence

by Diane K. Newman, RNC, MSN, CRNP, FAAN

There are basically four kinds of chronic urinary incontinence: Stress, Urge, Overflow, and Functional incontinence. They may occur alone, as is usually the case in the young adult, or in combination, as seen the elderly.

Stress Urinary Incontinence

Stress urinary incontinence is the involuntary leakage of small amounts of urine in response to increased intra-abdominal stomach pressure. Incontinence occurs during physical exertions when you sneeze, cough, laugh, or lift heavy objects.

Stress urinary incontinence is seen predominantly in women and is present in about 35 percent of incontinent elderly persons. The pelvic muscle is the key muscle in the pelvis that controls urine loss during increases of intra-abdominal pressure. Stress urinary incontinence results from either weakened support of the pubococcygeus and levator ani muscle and other pelvic structures or sphincter weakness/damage. Increasing levels of two neurotransmitters, serotonin and norepinephrine, found in the sacral spinal cord (Onuf's nucleus) can lead to an increased contraction of the external urethral sphincter. A new medication called duloxetine contains these neurotransmitters and will be the next treatment for stress urinary incontinence. Typically, this type of urinary incontinence occurs in women in whom childbirth caused a relaxation of the pelvic and periurethral musculature. It also occurs in men who have undergone prostate surgery and have lost function of the urethral sphincter that surrounds the prostate.

Urge Urinary Incontinence

Urge urinary incontinence is the leakage of larger amounts of urine that occurs when a person is not able to reach the toilet after the urge to void is perceived. Complaints include urine loss on the way to the bathroom or "key in the lock" syndrome. This type of urinary incontinence is part of the diagnosis of overactive bladder. Overactive bladder is a combination of urinary urgency, frequency and urge urinary incontinence.  Urge urinary incontinence is the most common (60-70%) pattern of UI in the older person. Detrusor instability, sometimes called "overactive bladder", also occurs with urge urinary incontinence and is associated with disorders of the lower urinary tract or neurologic system.

Urge urinary incontinence can be the result of several causes which include detrusor hyperreflexia (unstable bladder), tumors, stones, or diverticula. Since urge urinary incontinence can result from an urologic carcinoma, any asymptomatic hematuria (blood in the urine) must be referred for further evaluation. Persons with symptoms of urge urinary incontinence may also have a condition which is called detrusor hyperactivity with impaired bladder contractility (DHIC). These clients will strain to void and have urinary retention. Treatments for urge urinary incontinence include drug therapy and behavioral interventions.

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Overflow Urinary Incontinence

Overflow urinary incontinence accounts for 10-15% of urinary incontinence. Overflow leakage of urine occurs when there is a mechanical or functional obstruction of the urinary bladder outlet. The obstruction leads to overfill of the bladder and incontinence due to a detrusor contraction which occurs when a certain volume is reached. In this form of chronic urinary incontinence, the client usually does not know why she/he leaks urine and frequent dribbling is common. Often the sensation of bladder fullness is diminished and the stream of urine is weak. These symptoms occur secondary to an anatomic obstruction (i.e. enlarged prostate, urethral stricture) or an atonic bladder. An atonic bladder can result from neurologic injury, diabetic neuropathic bladder, or drug-induced atonia. Drug induced atonia can be caused by anticholinergics, narcotics, anti-depressants, and smooth muscle relaxants. Neurologic injury can be caused by spinal cord trauma or a stroke.

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Functional Urinary Incontinence

Functional urinary incontinence may occur after a major illness or in nursing homes. It accounts for 25% of the urinary incontinence seen in hospitals and results when a person has difficulty moving from one place to another. Sensory impairments (including poor vision, hearing, or speech which may influence success in reaching facilities and inability to notify caregivers of the need to use the bathroom) can cause functional urinary incontinence. The person's home environment, such as the lack of a readily accessible bathroom, may cause urinary incontinence. Usually the person complains that she/he "cannot hold my urine until I can get to the bathroom". This is usually due to decreased mental function, decreased functional status, and/or unwillingness to go to the toilet.

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References

Newman, DK. Managing and Treating Urinary Incontinence. Health Professions Pr. 2002.

Posted December 2003
Updated June 2009

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