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Urinary Incontinence

Urinary incontinence affects an estimated 8 million women. Urinary incontinence is not a normal part of aging (more than 75% of women older than age 80 years are continent).

ETIOLOGY

Urinary incontinence is a symptom for which the underlying etiology should be sought. The two most common forms of urinary incontinence in ambulatory women are genuine stress incontinence and detrusor overactivity. Currently, it is thought that most patients with genuine stress incontinence have abnormal anatomic support that interferes with normal urethral sphincter function. Such patients have an "anatomically disadvantaged" sphincter, which works well when its position is once again stabilized, either surgically or with a supportive vaginal device. It is well recognized that the events of vaginal delivery predispose to anatomic abnormalities. In addition to the common occurrence of urethrovesical junction hypermobility (and cystocele), injury to the sphincter innervation occurs in some women. This obstetric etiology appears consistent through multiple randomized studies that indicate that 20-33% of women develop stress incontinence after a single vaginal delivery. The use of episiotomy as currently practiced does not appear to influence the incidence of stress incontinence. Less commonly, genuine stress incontinence occurs without antecedent obstetric damage. Most of these patients have some process that produces marked increases in intraabdominal pressures (eg, chronic lung disease, severe straining during defecation, unusual occupational loads).

An important subgroup of patients with stress incontinence have neuromuscular insufficiency of the urethral sphincter itself. Many of these patients have undergone prior anterior vaginal dissection.

The etiology of detrusor dysfunction is less well understood, with approximately 90% of detrusor overactivity deemed idiopathic. The term detrusor instability is used to describe an idiopathic overactivity of the bladder smooth muscle. In the remaining 10% of patients, detrusor overactivity is caused by a well-recognized group of neurologic disorders. Systemic neurologic diseases such as multiple sclerosis and Parkinson's disease frequently cause lower urinary tract dysfunction. Detrusor overactivity commonly follows a stroke, during which ischemic damage occurs to the detrusor motor area of the cerebral cortex. When a recognized neurologic process causes detrusor overactivity, the term detrusor hyperreflexia.

Other less common forms of urinary incontinence may occur, including genitourinary fistula, ectopic ureter, and urethral diverticulum. These rare lesions must be kept in mind during the evaluation.

DETECTION OF INCONTINENCE

Obstetrician-gynecologists can facilitate the reporting of urinary incontinence by regularly inquiring about it. The fact that approximately one of five women who experience urinary incontinence do so after a single vaginal delivery suggests that this group should be questioned as part of routine postpartum assessment.

INITIAL EVALUATION

Once urinary incontinence is reported, an initial evaluation should focus on the severity of urinary leakage and the patient's goals for resolution of the problem.

The urinary diary is a mainstay of incontinence evaluation (Fig. 7). This simple instrument allows the patient to record voided volumes, leakage episodes (and amounts), and type and volume of fluid intake urinary incontinence, overactive bladder, blader, stress urinary incontinence, urine leak, bladder leak, leaking, urine. Although a 3- to 5-day diary is optimal, a single typical 24-hour period.

Patient History

The lower urinary tract history should be taken as part of a complete pelvic floor assessment. Symptoms of both storage and emptying phases of the bladder cycle should be determined.

INITIAL INTERVENTIONS

After initial testing, diagnosis and treatment options should be discussed with the patient. For most women, an initial intervention can be selected. Further testing should be considered for patients whose diagnosis remains unclear after initial testing.

Behavioral Interventions

Techniques for behavioral management are helpful to virtually every patient with urinary incontinence. Simple techniques include adjustment of type and volume of fluid intake after review of the urinary diary. Older patients frequently have a nocturnal diuresis of vascular volume that has pooled during waking hours.

Muscle Rehabilitation

Women with weakened pelvic floor muscles may benefit from muscle-training protocols. These are helpful for patients with detrusor overactivity or stress incontinence. Before recommending any exercise regimen, the physician should ensure that the patient is able to isolate and contract her levator ani complex.

Electrical Stimulation

Electrical stimulation has been demonstrated to improve continence in many patients. Transvaginal electrical stimulators are FDA-approved devices that are effective for approximately 50-60% of women with genuine stress incontinence and detrusor instability.

Vaginal Devices

A variety of vaginal devices for treatment of stress incontinence are marketed in North America. Modified pessaries provide additional suburethral pressure, and bladder neck support prostheses.

Pharmacotherapy

When the previously discussed behavioral modalities have not improved incontinence, pharmacotherapy may be considered. There are no ideal medications for treatment of incontinence. The goals of pharmacotherapy are to decrease inappropriate bladder contractions, increase urethral resistance, or both. The main class of medications used for treatment of detrusor overactivity affect the parasympathetic system by inhibiting bladder contractions. These anticholinergic medications are nonspecific, affecting cholinergic receptors throughout the body. Thus, therapy is frequently limited by systemic side effects such as dry mouth and worsening constipation. Narrow-angle glaucoma and certain cardiac conditions are absolute contraindications to these medications. Oxybutynin chloride is the only medication in this class with scientific evidence for efficacy. These medications are listed in Table 13.

Medications are less useful for stress incontinence than for detrusor instability. Clinical improvement of mild stress incontinence can occur with pharmacotherapy, whereas more severe incontinence typically requires alternative techniques. However, certain patients may benefit, particularly those with mixed incontinence.

Many over-the-counter cold and diet preparations contain alpha-adrenergic receptor stimulants such as phenylephrine or phenylpropanolamine. Imipramine hydrochloride is a useful incontinence medication that inhibits detrusor over-activity through its anticholinergic activity and increases urethral pressure via its sympathomimetic activity.

TABLE 13. Medications for Detrusor Instability

Drug Comments

Propantheline bromide Cure rates 60-80%; fewer side effects; variable gastrointestinal absorption

Oxybutynin hydrochloride Cure rates 60-80%; side effects in up to 75% of patients

Dicyclomine hydrochloride Effective if used parenterally

Flavoxate hydrochloride Limited data on efficacy; more expensive drug

Imipramine hydrochloride Cure rates 60-74%; beneficial for childhood nocturnal enuresis or mixed stress and

urge incontinence

SURGICAL INTERVENTION

When the patient refuses nonsurgical treatment or has persistent symptoms, surgical intervention may be considered for treatment of genuine stress incontinence. The goal of surgery for incontinence is to correct

Suburethral plication

Urethrovesical repositioning

--Abdominal urethropexy

--Needle urethropexy

Suburethral sling

Bladder neck implants

As a first-line procedure for stress incontinence with urethrovesical junction hypermobility, abdominal retropubic urethropexy procedures result in 85-90% objective cure rates. For these patients, who typically

Selection of primary surgery for incontinence should be based on anatomic support and sphincteric integrity. Before antiincontinence surgery for straightforward stress incontinence, the physician should document the

Symptoms: Pure stress incontinence (no nocturia, no urgency, no frequency, no voiding dysfunction)

Physical examination: Urethrovesical junction instability with movement of more than 30 degrees, no more than moderate anterior vaginal prolapse and adequate apical and posterior vaginal support

Postvoid residual volume: Less than 100 mL and sterile urine

Stress test: Objective evidence of transurethral loss with increased intraabdominal pressure

Cystometrography: Normal sensation, compliance, and detrusor activity

When these criteria are not met, the physician may consider additional lower urinary tract evaluation to confirm the diagnosis. Women with insufficient urethrovesical junction mobility (< 30 degrees) should not undergo retropubic repositioning procedures. This group of women largely overlaps with women who have intrinsic sphincteric deficiency. Alternative techniques such as suburethral slings or bladder neck.

Postoperative bladder drainage should continue until the patient is able to empty her bladder and her residual volume is less than 100 mL or less than one fourth of her voided volume. The choice of transurethral, suprapubic, or intermittent catheterization depends on the anticipated length of time needed for drainage.