Thomas E. Finucane
Urinary incontinence (UI) is defined in a variety of ways. Dorland's Medical Dictionary refers to “constant or frequent involuntary urination” due to failure of voluntary sphincter control. A more functional definition is “the involuntary passage of urine that causes problems for the patient or caregivers,” acknowledging that the definition of incontinence depends in part on social context. The wide variability in estimates of prevalence is due in part to differences in definition. The population-based prevalence of UI in women 30 to 90 years old may approach 50%. Severe UI has been reported by 8% of women in their 30s and by 33% of women in their 80s (1).
Defining and assessing severity and outcomes of treatment also are problematic. The perceived impact on quality of life is not always consistent with objective measures of urine loss. Some patients find the slightest degree of
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leakage intolerable, whereas others find daily use of multiple absorbent pads quite acceptable. Another factor that makes evaluation of treatments difficult is the natural history of the disease, which is chronic, fluctuating, and often progressive. Distinguishing treatment effect from natural variability can be difficult. Finally, psychological factors are central to the evaluation and treatment of UI; the problem is not simply one of urodynamics.
Pathophysiology
Urine flows when intravesical pressure exceeds urethral pressure. Innervation of the bladder is complex, but three important generalizations help in managing the various types of UI. The first generalization concerns the effects of upper motor neuron (UMN) and lower motor neuron (LMN) disease on bladder function. UMN lesions, such as stroke, cord injury, or multiple sclerosis, tend to cause loss of inhibition of reflexes, as they do with skeletal muscle, therefore leading to hyperreflexia of the detrusor muscle. In contrast, LMN lesions, such as diabetic neuropathy, interrupt the reflex arc and tend to cause flaccidity. (The term “neurogenic bladder,” which refers to either spastic detrusor contractions with UMN disease or a flaccid bladder with LMN disease, is ambiguous and should be avoided.)
The second generalization concerns autonomic innervation and can be remembered with the simple mnemonic that Sympathetics Sustain Storage. α-Adrenergic agents tend to increase urethral pressure and relax the detrusor, whereas adrenergic blockers have the opposite effect. Cholinergic agonists tend to relax the sphincter, whereas anticholinergics tend to increase sphincter pressure. Remembering this balance, the yin and yang of urine flow, allows ready understanding of drug therapy and of many unintended drug side effects.
The third generalization is epidemiologic. Young ambulatory women with UI most likely have predominately stress incontinence. In contrast, frail elders, especially nursing home residents, most likely have urge incontinence.
Clinical Syndromes
Stress Incontinence
Stress incontinence occurs when increases in intra-abdominal, and thus intravesical, pressure cause urine to leak, as with sneezing, laughing, coughing, lifting, or just rising from a chair. No detrusor contraction occurs. Although a variety of abnormalities, or combinations of abnormalities, can contribute to stress incontinence, the final common pathway is the same; pressure in the urethral sphincter is so low that a sudden increase in bladder pressure can overcome it, causing a leak of urine. Usually only small volumes of urine are lost in this form of UI. Nocturia and a sensation of urgency are absent.
Urge Incontinence
Patients with urge incontinence have, as the name suggests, a sudden irresistible urge to void. If the length of warning is shorter than the time required to reach a toilet, incontinence results. Often, large volumes of urine are lost. Involuntary detrusor contractions are the cause. These contractions are common in neurologically normal persons, in whom the term “detrusor instability” is often used; in patients with UMN lesions, “detrusor hyperreflexia” is the favored term. The terms uninhibited, spastic, hyperactive, overactive, and unstable bladder also refer generally to this situation, and the use of these terms has confused the literature in this field. Local irritation, as with stones, infection, or tumor, can cause or worsen urge incontinence, presumably by increasing afferent traffic in the reflex arc. In many cases, urge incontinence is idiopathic (2).
Overflow Incontinence
Patients with severe bladder distention can leak either small or large amounts of urine. Distention may occur because intravesical pressure is low, intraurethral pressure is high, or both. High intraurethral pressure in men is most commonly caused by prostatic enlargement, but most men with obstruction are not incontinent (see Chapter 53). In women, the most common cause of high intraurethral pressure is prior surgery. The most common cause of low intravesical pressure in both sexes is diabetic neuropathy.
Functional Incontinence
Some patients lack the motive, opportunity, or ability to reach a toilet in time. Cognitive, emotional, pharmacologic, and environmental factors all may contribute. Usually large volumes of urine are lost in this clinical form of UI.
Mixed Incontinence
In many patients, a combination of factors contributes to incontinence. These patients may present with a mixed picture, most commonly urge and stress incontinence. A relatively common problem is the incontinence pattern of stress-induced urge. Increases in abdominal pressure (and thus bladder pressure) induce an uninhibited bladder contraction and a sense of urgency followed by loss of urine, usually in large quantities. Detrusor hyperactivity with impaired contractility has been reported in frail elderly patients, especially in nursing home residents. Mild urge incontinence coupled with the inability to transfer
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independently (functional incontinence) in frail and impaired elders, especially those in nursing homes, is another common, recognizable presentation.
Recent-Onset Incontinence
The recent onset of incontinence in a previously continent patient is an important clinical problem. Recent-onset incontinence may be transient and reversible. In a patient who is otherwise stable, medication, urinary tract infection, and stool impaction should be considered. New UI can be an early sign of delirium or depression. UI can be devastating, often perceived by an older person as the beginning of infirmity and dependency.
Evaluation
History
The history begins with a commonsense evaluation for easily identifiable problems (Table 54.1). In cognitively intact patients, a clear history of urge or stress incontinence (or both) may be enough information to initiate a trial of therapy (3). In elderly men with incontinence, obstructive symptoms (hesitancy, weak stream) are predictive of overflow, but most men with prostatic obstruction are not incontinent.
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TABLE 54.1 Specific Areas to Cover in the History when Evaluating Patients with Urinary Incontinence |
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A bladder record or voiding diary can serve several functions. The patient is asked to record the date and time of each void or accident, circumstances, provocations (e.g., rushing to toilet suggests urge incontinence; coughing suggests stress incontinence), and volume (small suggests stress incontinence; large suggests urge incontinence). An initial diary provides a baseline measure of severity. The diary should include at least one 24-hour period; accuracy beyond a 3-day diary falls substantially. Cognitively impaired patients who cannot abstract and summarize their experience can benefit greatly from a caregiver-completed record, if a behavioral intervention can then be developed. Patients (and caregivers) who cannot complete such records may not be strongly committed to sustaining a treatment program for this chronic problem.
Medication history deserves special emphasis. First, sympathomimetic and anticholinergic drugs should be suspected as a cause of UI if bladder-emptying problems develop (as predicted by the mnemonic Sympathetics Sustain Storage). An elderly man who presents with urinary retention, for example, should be queried carefully about recent consumption of antihistamine–decongestant cold remedies or other new medications. Narcotics may cause urinary retention. In patients with limited cognitive reserve, any drug that interferes with executive function (decisions and interpretative reasoning) can provoke incontinence. Finally, rapid-acting diuretics can cause incontinence, but two points should be borne in mind. First, in a steady state, diuretics do not by themselves increase the total amount of urine a patient produces each day; daily urine volume in a steady state reflects daily fluid intake. Second, thiazide diuretics, especially when used at low doses for hypertension, actually have almost no diuretic effect. (How they lower blood pressure is uncertain, but the effect almost certainly is not due to intravascular volume contraction.)
Physical Examination
The examination should focus on identifying neuropsychiatric disease and impaired mobility. Marked extracellular fluid volume overload may be an important contributor, especially to nocturnal incontinence. A palpable bladder after an attempt to void is a significant but infrequent finding suggesting overflow incontinence. Fecal impaction is important to evaluate, especially if the UI is recent in onset or has worsened.
Signs of serious UMN or LMN disease usually are present elsewhere if bladder function is affected. In particular, a patient with new-onset UI who also develops signs of lower lumbar or sacral nerve dysfunction, such as abnormal perineal sensation, anal sphincter tone, or lower extremity strength, should be evaluated for cauda equina syndrome (see Chapter 86).
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Prostate size on rectal examination is neither sensitive nor specific for a diagnosis of outlet obstruction. Similarly, pelvic organ prolapse in elderly women is of limited diagnostic value in defining the cause or type of incontinence.
Further Testing
The value of measuring postvoid residual (PVR), by straight bladder catheterization or ultrasound, is uncertain. For healthy, ambulatory women with clear-cut stress incontinence, empiric treatment is justifiable. When the clinical situation is uncertain, and especially with elderly men, measurement of PVR will identify patients who do not empty adequately. This measurement is particularly important if a sympathetic agonist or anticholinergic drug is being considered. If the PVR is high, then the problem is more complicated than simply low pressures in the urethra (leading to stress incontinence) or uninhibited bladder contractions (leading to urge incontinence). Furthermore, the risk of hydronephrosis or recurrent urinary tract infection is increased. Authors vary in their definition of an “abnormal” PVR, and no absolute value can be invoked independent of the clinical picture. Further, PVR is by no means constant from measurement to measurement. A PVR that consistently exceeds 150 cc should most often be investigated further.
If the diagnosis remains so uncertain after the initial evaluation that a treatment plan cannot be clearly initiated, additional evaluation may be useful.
Cystometry
In bedside cystometry, a catheter is placed and through it the bladder is filled. The volume at which the urge to void is first felt, the volume at which the urge is uncontrollable, and any involuntary contractions all can be measured. Cystometry can be useful to assess bladder capacity and compliance, unstable bladder contractions, and sometimes bladder contractility. It can help clarify the diagnosis, for example, in an elderly male diabetic patient with symptoms of overflow incontinence. In this case, failure to empty completely might result from high intraurethral pressure due to prostate disease, low intravesical pressure due to autonomic neuropathy, or a combination of the two conditions. Proper treatment can be guided by these results.
Urodynamic Testing
The proper role of more invasive testing remains uncertain. Formal urodynamic testing provides a complete functional “snapshot” of bladder and urethral function. Manometric catheters placed in the bladder and rectum measure pressure in the bladder and abdomen, respectively. Fluid is instilled into the bladder, and the normal fill and empty cycle of the bladder is recapitulated. Patient sensation and awareness as well as intravesical activity can be assessed during filling (cystometrogram). The volumes at first urge to void and at uncontrollable detrusor contraction are determined. During voiding, bladder contractility, emptying efficiency, and rate of flow can be determined (pressure–flow study). To evaluate neurologic integrity, simultaneous electromyographic recording can be done at the external sphincter. Trials to evaluate the usefulness of urodynamic investigation are limited. Women who undergo these tests are more likely to undergo surgery or drug treatment, but evidence is insufficient to determine whether outcomes are improved (4). These tests can be uncomfortable, embarrassing, or both, especially for elderly patients.
Routine use of urodynamic testing for all incontinent patients is unjustifiable. These studies most likely will be useful in patients whose symptoms remain unacceptable with conservative therapy and who are willing to consider surgery. Patients who have not responded to surgery and patients with an underlying neurologic disorder also can be considered for urodynamic testing.
Urethrocystoscopy and imaging of the lower or upper urinary tract are not needed to evaluate isolated incontinence. However, these studies may be warranted if a tumor, stone, or foreign body is suspected, or if recurrent infection or laboratory abnormalities are to be evaluated.
Treatment
In general, treatment of stress incontinence emphasizes strategies to decrease sudden increases in abdominal pressure while increasing pressure in the urethral sphincter, and treatment of urge incontinence focuses on keeping bladder volumes low and anticipating the need to toilet. When incontinence is of mixed origin, both approaches should be taken. Effectiveness of the various interventions in UI is measured in a variety of ways, and direct comparisons are not always possible. Many of the reported trials were performed with few subjects and may not have had power to detect differences. Further, all of the medications touted as effective in treating patients with UI can have serious side effects.
General Principles
Several principles apply generally to the treatment of adult patients with UI:
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short intervals. A schedule may be suggested to cognitively intact patients, and scheduled toileting (i.e., by the clock) can help patients who are unable to toilet independently.
Urge or Mixed Incontinence
Several behavioral modification treatments are commonly used. Bladder training (also called bladder retraining) probably is effective for cognitively intact, mobile patients, but it requires an intensive, prolonged effort, including education, encouragement, and positive reinforcement (9). Patients are taught to recognize the sense of precipitate voiding and to postpone the urge by using distraction or relaxation techniques. The goal simply is to void on a schedule rather than in response to the urge to urinate. If the patient is unsuccessful in delaying the urge to void, the schedule can be redone, shortening the interval until the next scheduled void. Alternatively, the patient can simply stay on the same schedule and learn to ignore the interpolated voiding urges.
Evidence about bladder training is inconclusive but suggests that this intervention may be helpful. Habit training (also calledhabit retraining), which is distinct from bladder training, can be done when the patient has an identifiable pattern of voiding (e.g., when incontinence occurs after an avoidable stimulus, such as consumption of an iced drink). Bladder records are especially useful in this regard. The patient is toileted in anticipation of situations where incontinence is expected. Patients are best selected for habit training when they are unable to learn bladder continence, as they would in bladder training. Habit training usually is most suitable for patients who live at home with a caregiver. Evidence about habit training is insufficient to judge the effectiveness of the intervention. Most participants in clinical trials have been dependent elderly women.
The following techniques are suggested for bladder training:
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TABLE 54.2 Drug Treatment of Urinary Incontinence |
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Prompted voiding (also called timed voiding), another behavior modification modality, is attempted with patients who are cognitively impaired and unable to toilet independently. The protocol comprises monitoring for wetness, prompting the patient to void when wetness is identified, and then providing positive reinforcement after voiding. This treatment typically is used in nursing homes and assisted living homes. As with habit training, evidence to recommend for or against prompted voiding is insufficient.
Drug Therapy
Five anticholinergic drugs are approved for treatment of overactive bladder (10). Despite upbeat advertising, these drugs have very limited effects. For example, compared to placebo they reduce the average daily number of incontinence episodes by less than one. Frequency is also an endpoint in treatment of overactive bladder, and these drugs reduce the total number of micturitions by approximately one per day. Volume voided per micturition was improved by less than 2 tablespoons compared to placebo. Flavoxate, another heavily touted drug, is even less effective and should not be used. Except for generic oxybutynin, all of these drugs are expensive, and all cause anticholinergic side effects, especially dry mouth (Table 54.2).
Urge incontinence in men can be extremely bothersome and may result from bladder outlet obstruction, overactive bladder, or both. Because of the risk for urinary retention, drugs that interfere with emptying should be used with extreme caution in this population. Studies of anticholinergics generally include only a minority of subjects who are men. Many studies exclude men with evidence of voiding dysfunction or bladder outlet obstruction, and the subjects tend to be in their 60s. Some evidence suggests that the addition of an anticholinergic drug to an α-blocker is effective in men with bladder outlet obstruction and overactive bladder. In men with intolerable symptoms, a combination drug strategy is reasonable; collaboration with a urologist may be helpful. Dribbling after voiding is common in men and may be due to an enlarged prostate; α-blockers are sometimes useful.
Stress Incontinence
Treatments aim to raise pressure in the urethra, especially at the sphincter. Pelvic floor muscle exercises (PFME) are more effective in treating stress incontinence in adult women than is sham treatment or no treatment, although most women studied were premenopausal. A majority of women report significant benefit (11). The mechanism
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by which these exercises lead to improvement is uncertain. They also may be effective for men following radical prostatectomy (12). Stress incontinence is seen in men following radiation therapy or in the presence of UMN lesions, such as spinal cord injury or multiple sclerosis. PFME in these settings have not been found to be helpful. Referral to a urologist should be strongly considered for men with stress incontinence. For women, PFME often are combined with or compared to biofeedback, vaginal cones (a form of weight lifting), or electrical stimulation of the pelvic floor. The data are variable, but of these treatments, biofeedback seems to offer the best results. Many elderly women do not persist with PFME, although one study of women (mean age 50 years) found that 5 years later most were still doing the exercises at least weekly and were doing well (13).
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TABLE 54.3 Some Current Surgical Procedures Used to Treat Urinary Incontinence |
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Generally, PFME should be tried by patients with stress or mixed incontinence, because these exercises are relatively simple, are not harmful, and often are very effective. A patient may get a good sense of these exercises from reading the lay literature (see Burgio, et al.http://www.hopkinsbayview.org/PAMreferences). If the patient appears motivated but has not achieved success by doing the exercises suggested, he or she may benefit from referral to a multidisciplinary continence clinic.
The following techniques are suggested for PFME:
Bladder training (discussed for urge or mixed incontinence) has been reported to be useful in women with stress incontinence (9). Systematic data in men are limited, but the intervention is generally not burdensome and may be tried.
Evidence about drug treatment of stress incontinence is weak. Adrenergic drugs are toxic and only marginally effective. Studies show improvement of perhaps one less pad per day (14). Anticholinergic drugs may benefit some patients, especially those with mixed urge–stress pattern. Other drugs that enhance adrenergic transmission are being proposed but, as the Cochrane Collaboration observes, “More studiesare required, especially if conducted independently of pharmaceutical companies” (15).
Surgical Treatment
Surgical therapy for incontinence continues to evolve for both men and women. More than 100 procedures for
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incontinence have been described. Most have been abandoned, but a few are performed with acceptable levels of satisfaction and risk. The search continues for a minimally invasive, effective procedure that corrects or compensates for the variety of dysfunctions that cause incontinence.
There are few well-designed, randomized trials, and the lack of standardization in measuring outcomes makes comparisons difficult. However, procedures used by urologists and gynecologists have been variably successful, and none can be clearly shown to be a “gold standard.” The generalist considering referral of a patient for surgery should consider the impact of the incontinence, expectations for outcome, tolerance for risk, existing comorbidities, local surgical expertise, and preference. Surgery should be considered only if the patient has intolerable symptoms despite maximal conservative and pharmacologic treatment.
All procedures designed to correct incontinence in women carry potential risk for injury to the bladder, urethra, ureters, and bowel. Procedures to correct stress incontinence in men do not carry the same risk for collateral injury as they do in women. The gold standard is placement of an artificial urinary sphincter. There is some enthusiasm for a male sling, although this procedure is less effective and is associated with the potential for injury to the urethra and possibly the bladder. In women, procedures that attempt to suspend or support portions of the urethra and anterior vaginal wall can cause urinary retention. Urgency and worsened prolapses of other pelvic organs are risks of surgery. Because of anatomic proximity and shared innervation, changes in bowel and sexual function may be affected by incontinence surgery. Table 54.3 summarizes some of the surgical procedures currently used in women. “Cure” rates should be interpreted with caution. Studies of surgical procedures often are extremely heterogeneous with respect to design patient population, intervention, and outcomes. Few studies are rigorous, randomized trials. Optimistic results may be more likely to be published than negative results. Cure rates of 100% are reported in occasional studies.
Specific References*
For annotated General References and resources related to this chapter, visit http://www.hopkinsbayview.org/PAMreferences.