Urinary Incontinence

URINARY INCONTINENCE

Urinary incontinence may affect as many as two hundred million people around the world. Urinary incontinence is not well understood by those affected, or by health care workers. It is not a dangerous condition, but it has a huge influence on the sufferer’s quality of life. The International Continence Society, established in 1970, defines urinary incontinence as a condition where involuntary loss of urine is a social or hygienic problem and is objectively demonstrated.

Prevalence

Reports of the prevalence of urinary incontinence in women vary because of differences in the definition of urinary incontinence, the study samples, and underreporting due to variation in the methodology of surveys. The condition is more common in women. Systematic reviews conclude that there is a community prevalence of 20 to 30 percent in young adults, 30 to 40 percent in middle-aged women and 30 to 50 percent in elderly women. In long-term care institutions, the prevalence is higher. If incontinence severity is considered, however, the prevalence of bothersome or significant incontinence (i.e., that which is severe enough to have a significant impact on a person’s quality of life) is between 5 and 10 percent of the community. Initial data suggests that the prevalence is higher in caucasian women; though prevalence in noncaucasian women worldwide requires further study.

There is little information on the proportions of types of urinary incontinence. There are very few incidence studies, and remission may occur either naturally or with treatment. Urinary incontinence is more prevalent during pregnancy and following childbirth, menopause, and hysterectomy. Obesity, lower urinary tract symptoms (e.g., blood in the urine, urine cloudiness, and foul smelling urine or urinary burning), and problems with mobility (functional impairment) or thinking (cognitive impairment) are associated with urinary incontinence. The prevalence of urinary incontinence in men is half that of women and rises more gradually with age. In the United States alone, the economic impact of this condition has been estimated at 18 billion dollars per year, including costs for nursing hours, surgery investigations, pads, and devices for containing incontinence.

Neurological control

The urinary bladder, and the urethral sphincter (a muscular band around the urethra that prevents urine flow) are the two lower urinary tract structures, that together with the supporting muscular pelvic floor, are important for control of urination. Their functions are regulated by coordinated peripheral, autonomic (involuntary), and central (voluntary) nervous system control. The two phases of lower urinary tract function—urine storage and voiding (emptying)—are controlled by urine storage and voiding reflexes. In an infant, during urine storage, the bladder relaxes with filling and the sphincter, under autonomic nervous system control, remains closed. At a certain level of filling, a primitive spinal reflex causes sphincter relaxation and simultaneous bladder (detrusor) contraction, resulting in voiding of urine through the urethra. With maturation of the central nervous system pathways, continence is learned, with inhibition of the primitive spinal reflexes by voluntary control through the frontal cerebral cortex.

Causes of incontinence

The compression of pelvic nerves and the stretching of the pelvic floor during vaginal delivery can result in neuromuscular damage. The function of the urethral sphincter may thus be compromised, contributing to the higher prevalence of stress urinary incontinence (SUI; loss of urine with stress maneuvers such as coughing, laughing, or sneezing) in women who have had many children, compared with women who have had none. Aging and/or diseases that affect the peripheral, autonomic, or central nervous system control of continence, can also result in urinary incontinence. Some older men and women lose cerebral cortical control for unclear reasons, resulting in an unstable, ‘‘overactive’’ bladder (so called idiopathic detrusor instability). This condition is manifested by urinary urgency (e.g., the sudden need to void) and urgency incontinence.

Diseases affecting the cerebral cortex, such as strokes and multiple sclerosis, may result in bladder overactivity (detrusor hyperreflexia) because of central nervous system involvement. Diseases that affect the midbrain or spinal cord, such as multiple sclerosis and spinal cord injury, interfere with the coordination of sphincter relaxation during voiding. This loss of synchronization of sphincter relaxation with bladder contraction is termed detrusor-urethral dyssynergia, and results in voiding that is uncoordinated and incomplete.

Interference of bladder sensory nerves due to long-standing diabetes or physical injury to the pelvic motor nerves may result in loss of bladder sensation or contractility of the detrusor muscle. This causes the bladder to contract poorly, resulting in incomplete emptying of the bladder and urine retention. Obstruction to the flow of urine from the bladder commonly occurs in elderly men due to prostatic gland enlargement. Narrowing of the urethra (urethral stricture ) in men or women can also cause physical obstruction to urine flow, resulting in urinary retention and overflow incontinence. In older men, radical surgery for prostate cancer can interfere with sphincteric urinary control. However, urgency urinary incontinence is the most common type of incontinence in men, with lower urinary tract symptoms, functional and cognitive impairment, prostatectomy and urological conditions as recognized risk factors. This condition can be a symptom of an enlarged prostate.

In developing countries where health care resources are scarce, maternal birth injury due to obstructed labor is not uncommon. Injury to the urethra, bladder, and vagina can result in the formation of fistula, which are abnormal tracts that connect the bladder or urethra directly with the vagina, resulting in constant uncontrolled urine loss. For women affected, this is a devastating complication.

Post-menopausal estrogen decline may cause changes in the urogenital tract, especially shrinkage (atrophy) of supporting tissue. With age, pelvic muscle function is reduced and pelvic tissues lose elasticity. Obesity in older women increases abdominal pressure and may be a contributing factor to SUI.

Assessment

A detailed continence history, bladder diary, physical examination, and measurement of residual urine in the bladder after voiding are components of a continence assessment. Commonly questions are asked about congenital abnormalities, attainment of continence, previous urinary tract infections, obstetric history, neurologic diseases, and previous gynecologic surgery. Some medications have an adverse influence on lower urinary tract function and may promote incontinence. Questions about the quality, type, and timing of fluid intake over a twenty-four hour period; and about smoking, bowel pattern of function, sexual function, and quality of life, can identify reversible lifestyle factors. A one-week bladder diary captures frequency of voiding and wet (incontinent) events. A bladder diary can be repeated after treatment to show objective improvement. If continence pads are used, the number and type are noted. In some instances, measurement of the voided volume is helpful. The loss of urine with stress maneuvers such as coughing, sneezing, or exercise, or loss of urine with urgency may suggest the underlying mechanism of incontinence. Sometimes these symptoms occur together.

In women, the physical examination includes vaginal inspection for signs of post-menopausal estrogen deficiency, pelvic organ prolapse, urogenital fistula, and assessment of voluntary contraction of the muscular pelvic floor. In men, digital rectal examination assesses the size, symmetry, and consistency of the prostate gland, and the examination helps rule out prostate cancer.

Neurologic examination rules out diseases such as stroke, multiple sclerosis, and Parkinson’s disease, and also assesses the nerve and muscular function of the anal sphincter and sacral sensation. Mental state and mobility are also assessed in the elderly. The former will rule out dementia and assess the person’s ability to learn behavioral interventions.

Any urine remaining in the bladder after voiding is usually abnormal and can be measured by passing a catheter in and out through the urethra. Noninvasive assessment can be done by ultrasound examination of the bladder. Further in-depth assessment of the bladder and urethral structure may be indicated using a cystoscope inserted into the bladder through the urethra. The coordinated function of the bladder and urethra may be evaluated by further sophisticated urodynamic tests. These tests are indicated if there is no improvement with conservative behavioral interventions and drug therapy, or if surgery is contemplated.

Management

Attention to lifestyle issues is an essential part of management. A fluid intake of approximately 1,500 mls in twenty-four hours is usually an adequate amount, except in very warm environmental conditions. Excessive caffeine and alcohol intake will promote urine production and may increase urinary frequency. Fluid intake in the evening or at night may contribute to night-time voiding and incontinence. Smoking promotes coughing and is also associated with SUI. Attention to regular bowel function and avoidance of constipation is important.

Behavioral interventions may be effective in reducing or resolving urinary incontinence. These include timed voiding (bladder retraining) and pelvic muscle exercises. Pelvic muscle exercises can strengthen and improve the responsiveness of the pelvic floor and external sphincter. If the pelvic muscles are contracted rapidly during episodes of urinary urgency, the urgency may be suppressed. Biofeedback and electrostimulation are other modalities that have been tried for various types of incontinence with varying success.

Medications that relax or reduce bladder-muscle overactivity are often effective in reducing urinary urgency and urge incontinence. Side effects such as dry mouth or urinary retention may limit their use in some people, however. For overflow incontinence, medications that reduce the sphincter tone may improve bladder emptying. Intermittent catheterization two to three times per day or, rarely, an indwelling catheter, are appropriate options. Surgery in men to relieve prostatic obstruction that doesn’t respond to medication is often indicated. In women, estrogen replacement for symptoms of estrogen deficiency may reduce urinary urgency or frequency. For urogenital prolapse, vaginal support devices (pessaries) can resolve the prolapse, but not necessarily the associated SUI.

Stress urinary incontinence that doesn’t respond to behavioral interventions responds to a variety of injectable bulking agents, such as collagen, or surgical procedures in up to 90 percent of women. Five-year follow-up studies of these procedures show some return of incontinence. For bladder-vaginal fistula, surgery is successful in 50 to 100 percent of women. Containment of incontinence may be improved with specially designed absorbent pads or external catheter devices in men.

Prevention

The First International Conference for the Prevention of Incontinence, held in England in 1997, made a number of recommendations, including providing information to the public on healthy bladder habits, on when and how to seek help on supportive toilet training practices and attitudes by parents (and their effect on successful attainment of continence), as well as simply providing information that incontinence can be treated. Relatives of people with existing incontinence are likely a receptive group to target with information on treatment. For example, by age seven, 10 to 16 percent of boys and 5 to 15 percent of girls have bedtime incontinence (nocturnal enuresis). By age twelve, this prevalence is 5 percent in boys and 2 percent in girls. This benign delay in maturation will usually respond to appropriate advice on eating, drinking, regular daytime voiding, and reducing fluid intake later in the day.

For prenatal women, regular pelvic muscle exercises can improve the strength and function of the pelvic floor and may reduce the likelihood of postpartum stress urinary incontinence. Regulation of bowel function with diet, avoidance of constipation or straining during voiding also reduces the likelihood of stress incontinence or the falling down (prolapse) of the bladder or rectum into the vagina. Factors that contribute to maternal birth injury, such as childbearing in adolescent females (when pelvic growth is incomplete) and a lack of obstetrical services that can provide prompt Cesarean section, are potentially preventable.

In summary, urinary incontinence is a complex symptom that results from a variety of causes, requiring careful assessment of the type of incontinence and of contributing factors. Urinary incontinence will respond to a variety of measures. Generally, lifestyle and behavioral interventions, which are noninvasive, should be tried first. A positive message for those with incontinence who have never received assessment or treatment is that incontinence may be resolved, improved, or better contained in all sufferers.

Michael J. Borrie

See also Constipation; Menopause; Prostate; Sexuality.

BIBLIOGRAPHY

Abrams, P.; Khoury, S.; and Wein, A. Incontinence: Proceedings of 1st International Consultation on Incontinence, June 28–July 1, 1998, Monaco. Plymouth, U.K.: Health Publications Ltd., 1999.

Agency for Health Care Policy and Research. Urinary Incontinence in Adults: Acute and Chronic Management. Clinical Practice Guidelines No. 2, 1996 update, AHCPR publication No. 96-0682. Washington D.C.: U.S. Department of Health and Human Services, Agency for Health Care Policy and Research, 1996.

Canadian Continence Foundation. ‘‘Clinical Practice Guidelines for Adults.’’ Available on the World Wide Web at www.continencefdn.ca