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Urinary Incontinence in Women: Evaluation in the primary care office

Overview

Although not a threatening medical problem, urinary incontinence is a significant social problem for many women. The authors explain the four types of incontinence, ways to differentiate amount them with office procedures, and features of each type that effect choice of treatment. Nonsurgical management with drugs, strengthening exercises, hormones, self-catheterization, and mechanical devices is detailed.

One of the most common urologic problems in women is urinary incontinence. It will afflict nearly all women in some form during their lifetime and is of significant social concern to all women who experience it. This article provides the primary care physician with a practical and cost-effective approach to office diagnosis and nonsurgical treatment of the most common causes.

Anatomy and physiology

The lower urinary tract is functionally composed of a bladder and sphincter. Anatomically, the bladder consists of two segments, the bladder musculature (detrusor) and the trigone. The sphincter includes the bladder neck and the proximal urethra. Also important for urinary continence are the supporting structures of the pelvic diaphragm.

The detrusor muscle is innervated by the pelvic nerve via the parasympathetic (cholinergic) nervous system. The bladder neck and proximal urethra are innervated are innervated by the sympathetic (alpha-adrenergic) nervous system. The distal urethra is invested in skeletal muscle and is innervated by the pudendal nerve (figure l). The two major functions of the bladder are storage and expulsion of urine. A properly functioning and coordinated bladder and sphincter mechanism are required for continence. The bladder is responsible for accommodating increasing volumes of urine at low pressures. Normally, the bladder neck and urethra remain closed during bladder filling and at times of increased intraabdominal pressure (i.e., during coughing, laughing, or physical exercise). Continence is thus maintained as long as bladder neck and urethral pressure exceeds intravesical pressure. Voluntary voiding occurs when intravesical pressure exceeds bladder neck and urethral pressure under conscious and coordinated control. Voluntary voiding thus requires a bladder contraction and reciprocal relaxation of the bladder neck and urethral musculature. Incontinence is the pathologic condition that occurs when the intravesical pressure involuntarily exceeds the bladder neck and urethral pressure.

Classification

Urinary incontinence may be divided into four types: (1) stress (anatomic), (2) urge (detrusor instability or hyperreflexic bladder), (3) overflow, and (4) mixed stress and urge. The most common type in women is stress incontinence, which results from downward displacement of the bladder neck and urethra from their normal anatomic position behind the pubic symphsis. These patients experience the sudden loss of small volumes of urine during activities that increase intraabdominal pressure.

Urge incontinence---involuntary loss of large volumes of urine accompanied by symptoms of urgency, frequency, and nocturia--- is caused by an unstable bladder (detrusor instability). The patient may lose large volumes of urine with a change in position (i.e., from supine to upright) or with auditory stimulation (e.g., running water). In many cases, no neurologic or anatomic cause for bladder instability is evident. If objective evidence of a neurologic lesion is seen along with bladder instability, the patient is said to have hyperreflexic bladder. The most common causes of hyperreflexic bladder are spinal cord injury, cerebrovascular accidents, Parkinson's disease, and multiple sclerosis.

Stress incontinence, which causes the sudden loss of small volumes of urine during activities such as sneezing and coughing, is the most common type in women.

The loss of small volumes of urine because of bladder overdistention by a large amount of residual urine is referred to as overflow incontinence. This condition results from an underactive detrusor muscle, which is seen with smooth-muscle over-distention or neurologic problems (e.g., herniated disk, peripheral neuropathy of diabetes mellitus)¹. More than one type of incontinence may be present simultaneously.². For example, it is not uncommon for women with stress incontinence to also have urge incontinence from detrusor instability. Because surgical correction of the anatomic lesion may not correct the detrusor instability, recognition and documentation of the existence of both conditions may be helpful.

History

An accurate voiding history is essential for the proper classification of urinary incontinence in women. The first step should be to evaluate the characteristics of the incontinence, such as the body position in which it occurs (e.g., supine, upright, sitting); aggravating conditions (e.g., coughing, sneezing, running): pattern of occurrence (episodic or continuous); associated urologic features (urgency, frequency, dysuria, nocturia); volume of loss (a few drops, entire bladder contents); and the patient's awareness of the incontinence (sensible or insensible fluid loss).

The presence of other medical conditions that may cause incontinence (e.g., Parkinson's disease, diabetes mellitus, multiple sclerosis, pernicious anemia, cerebrovascular accidents, seizure disorders) should be ascertained. Chronic pulmonary disease and upper respiratory tract infection often exaggerate urinary incontinence because of the increased coughing that these conditions cause. Symptoms or history of urinary tract infection should be sought, because the frequency and urgency such infection causes may exaggerate incontinence. The presence of hematuria, especially if no urinary tract infection is found, suggests a pathologic condition of the urinary tract and necessitates a more thorough urologic investigation.

Certain drugs that have no pharmacological action on the lower urinary tract may exaggerate urinary incontinence.

The patient's gynecologic history is important in assessing her estrogen status. Estrogen-deficient states can result from use of medication (e.g., clomiphene (Clomid) or, more commonly, menopause. Estrogen deficiency may result in atrophic vaginitis or atrophic urethritis, which pre-disposes to urinary frequency and/or urgency and can exaggerate incontinence. A history of previous bowel, back, gynecologic, or bladder surgery is important, because such surgery could affect the anatomy and innervation of the lower urinary tract.

Finally, the history should include use of any medications that could cause dysfunction of the lower urinary tract. Table 1 is a partial list of such medications. It is important to remember that certain drugs (e.g., diuretics) that have no pharmacologic action on the lower urinary tract may exaggerate urinary incontinence.

Physical examination

In addition to performing the routine physical examination, the physician should do careful abdominal, pelvic, neurologic, and rectal examinations. The abdomen should be examined for a distended bladder, which suggests, overflow incontinence. The pelvic examination assesses the estrogen status of the vaginal mucosa. Atrophic vaginitis is usually accompanied by atrophic urethritis. A urethral caruncle is also evidence of hypoestrogenism. A search should be made for vaginal infection, which can often cause urinary incontinence. A neurologic examination is performed to assess the second, third, and fourth sacral nerves' sensory and motor supply to the pelvis and perineum. This includes the bulbocavernous reflex and perineal response to light touch and pinprick. Assessment of rectal sphincter tone and the presence or absence of rectal masses or fecal impaction completes the physical examination.

Laboratory tests

Urinalysis should always be performed when evaluating a patient for incontinence. The presence of hematuria, pyuria, bacteriuria, or glycosuria necessitates further investigation. Urine should be sent for culture if more that five white blood cells per high power field are present.

Commonly used drugs that can cause or exaggerate urinary incontinence:

Beta adremergics (i.e., used for asthma)
Alpha and beta blockers
Anticholinergics
Antidepressants
Antihistamines and alpha adrenergics (i.e., cold medications)
Calcium channel blockers
Anxiolytics
Narcotics
Analgesics
Diuretics

Office tests

Once a careful history and physical examination have been performed and a urinary tract infection has been ruled out or treated, several simple office procedures may be performed to define the nature of the incontinence. To institute appropriate therapy, the physician needs to differentiate between incontinence cause by a bladder contraction (detrusor instability) and that caused by an anatomic defect.

One test is measurement of the volume of voided urine. The patient should drink fluids to fill her bladder and then void into a measuring container. The volume of urine and mean flow rate (volume divided by the number of seconds taken to empty the bladder) should be recorded. A low volume may reflect a small bladder capacity caused by bladder instability, neurologic dysfunction, or anatomic changes in the bladder. A decreased flow rate (? ml/sec) indicates urethral obstruction or poor bladder contractility.

A large amount of residual urine in the bladder after voiding implies the presence of urethral obstruction or decreased bladder contractility.

Use of diaphragm to test whether bladder-suspension procedure will correct urinary incontinence. a. Normal retropublic position of the female bladder and urethra. b. Abnormal position of bladder and urethra seen in stress incontinence. c. Restoration of normal anatomy with insertion of diaphragm, suggesting anatomic weakness of bladder neck and urethra that will respond to surgery. Diaphragm can also be used to treat mild stress incontinence.

The amount of residual urine should be measured by placing a 14F or 16F catheter into the bladder. A large residual volume implies urethral obstruction or decreased bladder contractility. Difficulty in inserting the catheter may indicate a large urethral diverticulum or urethral obstruction. The latter, however, is quite rare in women.

With the catheter left in place, a bladder-filling test is performed. The catheter is attached to the open barrel of a 50-ml syringe, which serves as a funnel. The syringe is held about 15 cm above the public symphysis and filled with sterile water or saline solution, and the patient reports the first sensation of a full bladder (bladder capacity). When she voids, the fluid column within the syringe should rise, representing a bladder contraction. The physician should also note whether the patient can feel the bladder contraction and voluntarily inhibit it (i.e., the fluid in the syringe would recede).

Bladder instability typically results in urgency, with a bladder contraction that cannot be inhibited. If 250 ml of water or saline solution is instilled and no bladder contraction occurs, bladder instability in the supine position is unlikely. It is not unusual for a normal person to be unable to initiate a detrusor muscle contraction under these circumstances. If 600 ml is instilled without a sense of fullness, abnormality is present.

The Marshall-Marchetti test is useful in detecting stress incontinence. After the previously described tests have been performed, the bladder is again filled through the catheter. As the patient coughs or does the Valsalva maneuver, the physician observes the external meatus of the urethra for fluid loss. If this test does not elicit incontinence, the patient is asked to run in place and is observed for urinary leakage. Occasionally these maneuver provoke uninhibited detrusor contractions, which result in a large volume of fluid loss rather that the spurt that is seen in stress incontinence.

If continence is restored with insertion of a diaphragm, anatomic weakness of the bladder neck and urethra is probably present.

Many clinicians use the Bonney test to predict the success of surgery for incontinence. In this test, the examiner elevates the bladder neck on each side of the urethra with the fingers. However, this procedure may give false-positive results because the urethra is compressed (and may be occluded) against the pubis. False-positive results can be avoided by placing a slightly opened ring forceps in the vagina at the level of the bladder neck. The bladder neck is elevated with the ring forceps, and the patient is asked to cough or do the Valsalva maneuver. If the patient is continent during this procedure, the likelihood of success from a bladder-suspension procedure is high.

Another test used to assess the loss of support of the urethra and bladder neck is the cotton-swab test. A lubricated cotton swab is inserted into the urethra to the level of the bladder neck. The patient is asked to strain or do the Valsalva maneuver. Excursion of the cotton swab more than 20 degrees from horizontal is considered a positive result and suggests loss of anatomic support of the bladder neck and urethra.

The pessary or diaphragm test is useful in diagnosing stress incontinence.³. A suitable diaphragm or pessary is placed in the vagina after the Marshall-Marchetti and Bonney tests have been performed. If continence is restored, an anatomic weakness of the bladder neck and urethra is probably present, and a good result can be anticipated from a bladder-suspension procedure. We believe this test does not occlude the urethra against the pubis but restores the urethra and bladder neck to their normal retropubic position (figure 2).

Nonsurgical treatment

The most practical management of urinary incontinence consists of promoting either bladder emptying or bladder storage, depending on the type of problem that the patient has.⁴ Pharmacologic agents. may be used to inhibit involuntary bladder contractions and to increase bladder outlet resistance. A minor anatomic defect may respond to treatment with a mechanical device.

PROMOTING BLADDER EMPTYING

Bladder emptying can be accomplished by increasing intravesical pressure or decreasing outlet resistance. The drug most commonly used to promote contraction of the detrusor muscle is the cholinergic agent bethanechol (Duvoid, Urecholine). The therapeutic range is 10 to 50 mg. four times a day. Dosage is titrated by measuring the residual volume, which should be less than 10% of bladder capacity. The side effects of bethanechol are abdominal cramps, diarrhea, nausea, and sweating. The drug is contraindicated in patients with asthma.

Candidates for intermittent self-catheterization should be strongly motivated, have adequate fine motor dexterity of the upper extremities, and have a normal urethra.

Outlet resistance can be decreased by alpha-adrenergic blockers. This class of drugs blocks the sympathetic nerves to the internal sphincter at the level of the bladder neck. Use of phenoxbybenzamine (Dibenzyline), 10 mg. Twice a day, has been effective in promoting bladder emptying in patients with both functional and anatomic obstruction at the level of the bladder neck. The most common side effect is orthostatic hypotension, and all patients should be warned of this potential complication. We suggest that phenoxybenzamine be used only for a short period, because carcinogenic activity has been associated with prolonged use of the drug in laboratory animals.⁵. Recently, prazosin (minipress) has been reported to be effective in reducing outlet resistance at the bladder neck level by alpha-adrenergic blockade.⁶ The effective dosage is 1 to 6 mg. Twice a day. Side effects include reflex tachycardia, nasal congestion, and retrograde ejaculation. In addition, patients taking prazosin commonly experience orthostatic hypotension. Badlani and Smith⁷. have recommended that a started dose of 1 mg be given before bedtime for several weeks before increasing to the therapeutic dose.

If pharmacologic therapy is unsuccessful in promoting bladder emptying, intermittent clean (nonsterile) self-catheterization can be used safely and effectively by children, adults, and the elderly as outpatients.⁸. Candidates for intermittent self-catheterization should be strongly motivated, have adequate fine motor dexterity of the upper extremities, and have a normal urethra (i.e., no urethral strictures). The suggested schedule for self-catheterization is every three hours during the day and once or twice during the night (or often enough that urine volume is less than 300 ml). A 14F clear plastic catheter made for this purpose (e.g., Mentor Self-Cath^*) can be used. It can be cleaned with ordinary soap and water and can be inserted without lubrication. Most patients do not require antibiotics.

Kegel exercises are an effective and inexpensive method of managing mild stress incontinence, but many women do not adhere to them for the months required to see improvement.

PROMOTING BLADDER STORAGE

Bladder storage can be accomplished by increasing bladder outlet resistance or by decreasing intravesical pressure. The patient can be taught to perform Kegel exercises, which strengthen the pubococcygeal periurethral muscle fibers and augment bladder outlet resistance. The patient is initially instructed to practice the exercises by voluntarily starting and stopping the urine stream. Once the patient recognizes what muscle groups are involved, she can practice the exercises when not urinating. The patient should contract the pubococcygeal muscles for three seconds, relax, and repeat the exercises ten times. This sequence should be done five to ten times each day. Most women do not notice any change in their symptoms for several months after beginning the exercises. However, one study⁹ reports a 75% improvement after six months in patients with mild stress incontinence. This is an effective and inexpensive method of managing mild stress incontinence. Unfortunately, many women fail to adhere to the exercises when they do not see improvement after several weeks.

Estrogens are effective in the management of the postmenopausal woman with mild to moderate stress incontinence. in postmenopausal women, use of topical or oral estrogens can improve the vascularity of the Urethral mucosa and thus increase urethral resistance.¹⁰ The best response is obtained after 2 gm of conjugated estrogen cream is inserted into the vagina every other day. The dose can be reduced to 1 gm after a response occurs.

PHARMACOLOGIC MANAGEMENT

The two classes of drugs used for inhibiting involuntary bladder contractions are true anticholinergic agents and smooth-muscle relaxants.

Propantheline (pro-Banthine) is the most commonly used anti-cholineric agent for treating involuntary bladder contractions. It acts by competitive blockage of cholinergic receptors in the bladder wall. The oral dosage is 15 to 30 mg three or four times a day. The most common side effects are dry mouth, blurry vision, drowsiness, constipation, and increase heart rate. Its' use is contraindicated in patients with glaucoma and significant bladder outlet obstruction.

Smooth-muscle relaxants, such as oxybutynin (ditropan) and flavoxate (Urispas), reportedly act directly on smooth muscle at a site distal to the cholinergic receptor. These agents cause some anticholinergic activity and possess local-anesthetic properties as well. The usual dosage for oxbyutynin is 5 mg two to four times a day, and for flavoxate it is 100 to 200 mg. Three times a day. The potential side effects are identical to those of propantheline.

Tricyclic antidepressants such as imipramine (Janimine, SK-Pramine, Tofranil), are also useful for promoting urinary storage. While the exact mechanism of action is unknown, imipramine has anticholinergic and adrenergic effects. Clinically, imipramine decreases bladder contractilility and increases bladder outlet resistance. The usual dosage is 25 mg four times a day, with a gradual increase to 150 mg as a nighttime dose. The most common side effects are related to the anticholinergic effects and are like those of propatheline. Imipramine is contraindicated in patients receiving monoamine oxidase inhibitors and should be used with caution in patients with hypertension or cardiovascular disease.

Pharmacologic agents that increase bladder outlet resistance can improve mild to moderate stress incontinence. sympathomimetic drugs, such as ephedrine, pseudoephedrine, and phenylpropanolamine, act by stimulating the alpha-adrenergic receptors of the bladder neck and proximal urethra. The dosage of ephedrine is 25 to 50 mg four times a day. Pseudoephedrine is given in a dosage of 30 to 50 mg four times a day and phyenlpropanolamine in a dosage of 50 mg three times a day. Over- the-counter medications used for relief of allergic rhinitis that contain phenylpropanolamine, isopropramide, and chlorpheniramine (Contac 12 hours caplets, Triaminic 12 tables) are useful for treating mild stress incontinence. Side effect of the sympathomimetic agents include hyper-tension, anxiety, and insomnia From CNS stimulation. These agents should be used with caution in patients who have hypertension, cardiovascular disease, or hyperthyroidism.

Mechanical devices

Vaginal pessaries have been used to treat problems associated with pelvic relaxation including stress incontinence.¹¹ The pessary may alleviate stress incontinence in women who have mild anatomic defects. Baum and Suarez¹² recently reported their experience using a diaphragm to control mild stress incontinence, especially when it was present only during exertion.

Use of an indwelling catheter should be avoided if at all possible. However, it may be necessary in patients with decubitus ulcers (urine promotes skin maceration) and patients who are unable to perform intermittent self-catheterization.

Summary

Urinary incontinence in women is common and can be a significant social problem. The most common type is stress incontinence, caused by displacement of the bladder neck and urethra and experienced during activities that increase intraabdominal pressure. Other types are urge overflow, and mixed incontinence. Diagnosis of the type and cause can usually be made using simple, cost-effective office procedures. Nonsurgical treatment is often successful and may consist of pharmacologic management. Intermittent self-catheterization, Kegel exercises, and use of a mechanical devise.

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Reprinted with permission from Dialog Medical, dialogmedical.com

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