Urinary Incontinence

Urinary incontinence is defined by the International Continence Society (ICS) as “the complaint of any involuntary leakage of urine.” As broad as this definition is, it is easy to see why the reported prevalence of urinary incontinence in women varies widely with differences in populations studied, methods of data collection, and specific definitions of disease. Incorrect estimates may result from biases in sample surveys, such as selection and respondent bias. Studies have shown moderately strong agreement between patient self-report and clinicians’ assessments of urinary incontinence. For these reasons, estimates from the literature should be considered as close approximations only.

Considerable variation exists in the estimated prevalence of any urinary incontinence, that is, any urine loss during a 12-month period in women in the community. When the continence mechanism is subjected to extreme forces, a significant prevalence is present even in women not traditionally thought to be at risk for urinary incontinence, such as nulliparous elite athletes (e.g., trampolinists) or female paratroopers. Among adult women in the community, the prevalence of any urinary incontinence ranges from 9% to 69%.

Severity of incontinence can be characterized by the frequency of incontinent episodes, quantity of urine lost, or both. When the severity of urine loss is defined as “daily,” “weekly,” or “most of the time,” the reported prevalence ranges from 3% to 17% for women in the community. This estimate corresponds more closely to the clinical estimate of disease because it probably identifies women at the more severe end of the spectrum who present for clinical care. The prevalence of urinary incontinence in women in nursing homes is much higher than in women in the community, with most studies reporting prevalence greater than 50%, especially in facilities where residents have more severe functional impairments.

Much less information is available on incidence, progression, or remission, compared with prevalence, for urinary incontinence (and even less for all other pelvic floor disorders). Young and middle-aged women develop urinary incontinence at a lower rate, 3% to 8% per year, than older women. Herzog et al. (1990) reported a 20% incidence of incontinence per year in women age 60 and over. However, Grodstein et al. (2004) reported a much lower incidence per year of 3.2% occasional and 1.6% frequent incontinence in women ages 50 to 75. As noted earlier, this emphasizes the difficulty of directly comparing findings across the literature due to the use of different definitions of disease.

Traditionally, urinary incontinence has been viewed as a chronic progressive disease. However, recent findings challenge this. In a 3-year study of raloxifene for osteoporosis, most women (60%) with incontinence at baseline did not experience a significant change in their symptoms; 27% improved, and only 13% worsened. Remission occurs in 6% to 38% of young and middle-aged women versus 10% in older women. These estimates include both chronic and acute causes of urinary incontinence. Incontinence due to transient causes, such as infection, drug use, and delirium, often regresses after treatment. Thus, a yearly fluctuation occurs in the development and regression of incontinence among individuals.

Fecal Incontinence

As with urinary incontinence, the reported prevalence of fecal incontinence varies by the definition used and the population surveyed. Unlike urinary incontinence, however, even the term itself is problematic. Some clinicians refer to fecal incontinence only for loss of stool (liquid or solid) and prefer anal incontinence to collectively describe loss of stool or gas; however, many others do not make that distinction and use fecal incontinence to refer to loss of any bowel contents, whether gas or stool. For the purposes of this chapter, the term fecal incontinence will refer to the involuntary loss of gas and stool (either or both). No consensus is known as to what constitutes severe or clinically important fecal incontinence. Severity can be expressed by the type of loss (gas, liquid stool, or solid stool) or the frequency of incontinent episodes. Several scales combine these two components and express the level of symptoms as a numeric score. Many studies use frequency of incontinent episodes of once a week or more, or loss that requires sanitary protection, to define fecal incontinence.

The prevalence of fecal incontinence in the general population ranges from 1.5% to 2.3%. In the elderly, the prevalence is higher, ranging from 3.7% to 18.4%. Women in nursing homes experience fecal incontinence at an even higher rate of at least 30% and up to 63%. Information on the incidence of fecal incontinence is unavailable, as is information on progression from mild or infrequent fecal incontinence to more severe forms.

Pelvic Organ Prolapse

Epidemiologic characteristics of prolapse are even more difficult to determine than those of urinary and fecal incontinence. Symptoms associated with prolapse are nonspecific, and the presence of mild to moderate prolapse cannot be determined reliably by questionnaire assessment without confirmation by physical examination. Although a standardized staging system for prolapse has been accepted by the ICS, no consensus exists as to what level of physical findings defines clinically significant prolapse. Reports of prevalence in the medical literature must be viewed with these limitations in mind.

In studies of women who were not seeking care for prolapse, mild to moderate prolapse (at or above the hymen, stages I–II prolapse by ICS standards) has been found in up to 48% of women. More advanced prolapse (beyond the hymen, stage III or IV) occurs in about 2% of women. In 412 women enrolled in the Women’s Health Initiative, Handa et al. (2004) reported an annual average incidence of 9.3 cases of anterior vaginal prolapse, 5.7 cases of posterior vaginal prolapse, and 1.5 cases of uterine prolapse per 100 women per year. In women with at least grade 1 prolapse at baseline, progression occurred in 10.7 cases of anterior vaginal prolapse, 14.8 of posterior, and 2.0 of uterine prolapse per 100 women per year. Interestingly, regression occurred more commonly than incidence or progression, especially from grade 1 to grade 0. Anterior vaginal prolapse regressed from grade 1 to 0 in 23.5 cases per 100 women per year, and from grades 2 to 3 to 0 in 9.3 cases per 100 women per year. Posterior vaginal prolapse regressed in 25.3 cases, as did uterine prolapse in 48 cases per 100 women per year. This serves to emphasize that prolapse is a dynamic condition, and factors related to progression and remission need further study.

Concomitant Pelvic Floor Disorders

Clinicians are well aware that pelvic floor disorders commonly occur together, although evidence in the literature has only recently confirmed this. Urinary and fecal incontinence (“double incontinence”) coexists in up to 69% of women. Different populations and differing definitions for both types of incontinence are responsible for some of the variation in reported results. Because symptoms of all pelvic floor disorders tend to be underreported by patients, clinicians are required to inquire routinely as to the spectrum of disorders whenever a patient presents with one symptom.

Sex

Urinary incontinence is two to three times more common in women than in men. The gender difference is most pronounced among adults under age 60 because of the very low prevalence of urinary incontinence in younger men. These sex differences are consistent, whether the measure is any incontinence, severe incontinence, or irritative bladder symptoms. The symptom of stress incontinence is uncommon in men who have not had surgery, but voiding problems are more common, especially in elderly men, in part due to prostate conditions.

The comparison of fecal incontinence between men and women depends on the population studied. Many studies show a higher prevalence of fecal incontinence in women than in men, although some studies report similar rates, and, in a few studies, men had higher rates than women. Women are uniquely susceptible to damage to fecal continence mechanisms at vaginal childbirth, but its influence toward the prevalence and causes of fecal incontinence in women compared with men is unknown. Studies of anorectal function show that, compared with men, women have lower anal squeeze pressures, greater perineal descent, and more evidence of nerve damage to the pelvic muscles and anal sphincters.

Although only women are at risk for pelvic organ prolapse, rectal prolapse affects men and women in approximately equal proportions, which requires an explanation that does not rely on damage incurred at childbirth.

Age

The prevalence of urinary incontinence increases with age, although it is not a linear relationship. Recent studies show a broad peak in prevalence from ages 40 to 60, with a steady increase occurring after ages 65 to 70 (Fig. 4-1). The type of incontinence may differ by age, with many studies suggesting a higher prevalence of stress incontinence in younger women, compared with more urge incontinence in older women; however, not all studies confirm this, and the prevalence of mixed (stress and urge) incontinence varies widely in different studies.

Figure 4-1 Prevalence of urinary incontinence by age group and severity.

(From Hannestad YS, Rortveit G, Sandvik H, Hunskaar S. A community-based epidemiological survey of female urinary incontinence: the Norwegian EPINCONT Study. J Clin Epidemiol 2000;53:1150, with permission.)

Urinary symptoms are found in over half of institutionalized elderly women. In addition to lower urinary tract dysfunction contributing to incontinence, nonurologic causes of incontinence, such as cognitive impairment, immobility, medications, and metabolic causes of excess urine output (e.g., diabetes) are often present. Jirovec and Wells (1990) observed that when multiple variables were examined together, mobility emerged as the best predictor of urinary control, followed by cognitive impairment. Therapy should always include a combination of urologic treatments with nonurologic treatments in dealing with urinary incontinence in the elderly, particularly in nursing home residents.

Most studies of fecal incontinence show increased prevalence with age. In a study of over 10,000 men and women in the United Kingdom, Perry et al. (2002) reported fecal incontinence in 0.9% of adults ages 40 to 64 and in 2.3% age 65 and over. Also from the United Kingdom, Crome et al. (2001) reported that the rate of fecal incontinence roughly doubled by decade of age, from 4.7% in women ages 70 to 79, to 10.1% in women ages 80 to 89, to 20.3% in women ages 90 to 99. As with urinary function, the effect of age on anorectal function is multifactorial, and the presence of comorbid conditions contributes to worsening symptoms. Incontinence, both urinary and fecal, is strongly associated with cognitive impairment and physical limitations.

Although available data are limited, virtually all studies show that the prevalence of pelvic organ prolapse increases steadily with age. This has been shown in case-control studies, prospective studies, and studies of surgery for prolapse. In the Women’s Health Initiative, at baseline, uterine prolapse was observed in 14.2% of 16,616 women. Anterior vaginal prolapse was observed in about one-third of the study population, regardless of hysterectomy status (32.9% with and 34.3% without hysterectomy); posterior vaginal prolapse was present in about one-fifth, similarly unrelated to hysterectomy (18.3% and 18.6%, respectively). For uterine prolapse, regression analyses showed a 16% to 20% increase in the odds ratio (OR) for having prolapse by decade of life. Studies of surgery for prolapse, which are likely to reflect the more severe end of the clinical spectrum of prolapse, consistently show increased rates of surgery by age (until age 80 and above). Olsen et al. (1997) reported prolapse surgery rates (per 1000 women per year) of 1.24 for women ages 50 to 59, 2.28 for those ages 60 to 69, and 3.43 for those ages 70 to 79.

Race

Racial differences have been reported for some pelvic floor disorders, although it is not yet clear whether the differences are biologic or sociocultural (related to health care access or likelihood of seeking health care), both, or other factors. Different levels of risk may be based on genetic or anatomic attributes; lifestyle factors, such as diet, exercise, and work habits; or cultural expectations and tolerance of symptoms. Populations traditionally thought to enjoy relative protection from pelvic symptoms have been shown, under closer study, to have a significant prevalence of urinary incontinence and other urinary symptoms, including black, Hispanic, and Asian (Japanese, Chinese) women. Differences may be present in the distribution of presenting symptoms or confirmed diagnoses, with some reports suggesting a lower risk for stress incontinence and a higher risk for detrusor overactivity in black or Hispanic women than in white women. However, these reports are not population based, which would provide the best estimate of true racial differences.

No reports related to race or ethnicity are available for fecal incontinence.

In many studies of prolapse, the populations are predominantly white, thereby limiting analyses related to race and ethnicity. In studies that do have significant minority representation, differences seem to appear in the occurrence of prolapse by race. In the Women’s Health Initiative, black women had a lower risk of prolapse (odds ratio of 0.65 or less), compared with white women. Hispanic women had a higher risk of uterine and anterior vaginal prolapse, with odds ratios of 1.24 and 1.20, respectively; the risk of posterior vaginal prolapse was not significantly different compared with white women. In a case-control study of 447 women, Swift et al. (2001) reported a statistically significant lower risk for prolapse in women of nonwhite race (although the magnitude of the lowered risk was not reported). Racial differences in the bony pelvis may play a role in determining a woman’s risk of prolapse, possibly by influencing the likelihood or extent of injury to pelvic support at childbirth.

Childbirth

Parity is a well-established risk factor for urinary incontinence in young and middle-aged women (up to age 50); however, the effect of childbirth diminishes with age and even disappears in older women. Large randomized trials (Heart and Estrogen/Progestin Replacement Study [HERS]) and observational studies (the Nurses’ Health Study) have shown no or weak effects of parity in older women. The prevalence of incontinence was 50% in a study of 149 nulliparous nuns, with two thirds of incontinent women having stress or mixed symptoms.

Early after delivery, the type of delivery has the strongest effect. In one of the few randomized trials of delivery type to address this (although not as a primary aim), the Term Breech Trial (Hannah et al., 2002) found less urinary incontinence in the planned cesarean delivery group (4.5%, relative risk 0.62) compared with the planned vaginal delivery group (7.3%) at 3 months postpartum. Because 43% of women in the planned vaginal delivery group actually had cesarean delivery, the results of this study probably underestimate the magnitude of the early difference between cesarean and vaginal delivery.

In a large community-based observational study in Norway of women less than age 65 (the Epidemiology of Incontinence in the County of Nord-Trondelag [EPINCONT] study), the prevalence of any incontinence was 10.1% in nulliparous women, compared with 15.9% in women delivered by cesarean, and 21.0% in women who delivered vaginally. The effect of delivery type diminished with age, such that the prevalence of incontinence was similar regardless of the type of delivery in the oldest age group of women studied (ages 50 to 64). Viktrup (2002) showed that incontinence 5 years after the first delivery was not influenced by the type of delivery. A study by Wilson et al. (1996) showed that the risk of incontinence accumulated with the number of cesarean deliveries; after three or more cesarean deliveries, the prevalence of incontinence was similar (38.9%), compared with women who delivered vaginally (37.7%).

In the few studies that have directly evaluated anorectal function in pregnancy, no changes have been consistently identified. Few women develop new symptoms of fecal incontinence during pregnancy (in contrast to urinary incontinence), although this has not been well studied. However, fecal incontinence or other symptoms of disordered defecation, especially fecal urgency, develop commonly after vaginal delivery. The risk of fecal incontinence for women delivering vaginally is highest in those who sustain direct anal sphincter damage (third- or fourth-degree perineal laceration). Symptoms of fecal urgency and incontinence to gas occur in up to 50% of women in the early postpartum period; loss to liquid or solid stool is less common but still significant, at 2% to 10%. Subsequent vaginal delivery, particularly if another anal sphincter laceration occurs, is associated with a higher risk of persistent fecal incontinence symptoms. The increased risk of fecal incontinence with anal sphincter damage persists and worsens with time.

Most studies show midline episiotomy as one of the strongest risk factors for anal sphincter damage and, therefore, fecal incontinence. Especially because current methods of surgical repair leave persistent anal sphincter defects in up to 85% of women and are associated with high rates of postpartum symptoms, it is critically important to prevent the initial damage at vaginal delivery. Even cesarean delivery does not protect women completely from the possibility of postpartum anorectal dysfunction. Recent studies have identified new fecal incontinence symptoms even after elective cesarean delivery without labor. At this point, it is unknown whether this reflects changes due to pregnancy, the surgical delivery, or possibly both.

Most (but not all) studies show that parity is linked to the prevalence of prolapse, although the magnitude of the effect varies in different studies. Mant et al. (1997) reported a strong cumulative effect of parity on the risk of inpatient admission for prolapse. The effect was greatest for the first and second births and less so for three or more births (Fig. 4-2). In cross-sectional data from the Women’s Health Initiative, Hendrix et al. (2002) found that the first birth approximately doubled the risk of uterine prolapse and anterior and posterior vaginal prolapse; each additional birth increased the risk by 10% to 21%. In longitudinal data from a subset of women enrolled in the Women’s Health Initiative, Handa et al. (2003) showed that the incidence of anterior vaginal prolapse increased by 31% for each additional pregnancy; similar associations were seen for uterine and posterior vaginal prolapse, although specific data were not reported.

Figure 4-2 Adjusted effects of parity on inpatient admission rates for genital prolapse. Relative risks adjusted for age, parity, or calendar period, as appropriate.

(From Mant J, Painter R, Vessey M. Epidemiology of genital prolapse: observations from the Oxford Family Planning Association Study. Br J Obstet Gynaecol 1997;104:579, with permission.)

Beyond parity, the type of delivery (i.e., spontaneous versus operative vaginal delivery; vaginal versus abdominal delivery; abdominal delivery with or without labor) and its association with subsequent prolapse has not been well studied. Two case-control studies have identified operative vaginal delivery (either vacuum or forceps) as a risk factor in women who undergo surgery for prolapse or urinary incontinence. However, conclusions regarding the relative effect of different modes of delivery cannot be made at this time, due to limited data.

Menopause and Estrogen

The vagina and urethra have similar epithelial linings because of their common embryologic origin. Urinary cytologic changes are similar to those of vaginal cytology during the menstrual cycle, during pregnancy, and after menopause. The classic estrogen receptor (ER-α) has been identified throughout the pelvis; the second estrogen receptor (ER-β), discovered in 1996, has not yet been well characterized. Urogenital atrophy due to estrogen deficiency is at least partly responsible for sensory urinary symptoms and decreased resistance to infection often found after menopause. Estrogen treatment administered vaginally reduces bladder infections in postmenopausal women with recurrent infections and may improve sensory lower urinary tract symptoms.

Related posts:

Obliterative Procedures for Vaginal Prolapse Evaluation of Urinary Incontinence and Pelvic Organ Prolapse: History, Physical Examination, and Office Tests Lower Urinary Tract Infection Surgical Treatment of Vaginal Vault Prolapse and Enterocele Urethral Injection of Bulking Agents for Intrinsic Sphincter Deficiency Bladder Drainage and Urinary Protective Methods

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