Urinary incontinence

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Chapter 37 URINARY INCONTINENCE

Theodore O’Connell

Urinary incontinence is caused by disturbance in the storage function, and occasionally in the emptying function, of the lower urinary tract. A continent sphincter mechanism requires proper angulation between the urethra and the bladder, as well as proper positioning of the urethra so that increases in intra-abdominal pressure are effectively transmitted to the urethra.

Women may undergo an anatomic or neuromuscular injury during childbirth but remain clinically asymptomatic as long as there is compensation by other components of the continence mechanism. Incontinence may not manifest in a woman until she loses a small percentage of muscle strength and innervation in the urethral sphincter as a result of aging or other injuries.

Stress incontinence is the involuntary loss of urine during an increase of intra-abdominal pressure. Stress urinary incontinence arises when bladder pressure exceeds urethral pressure during activities such as coughing, laughing, or exercising. The underlying abnormality is typically urethral hypermobility caused by a failure of the normal anatomic supports of the bladder neck. Intrinsic urethral sphincter deficiency, the lack of normal intrinsic pressure within the urethra, may also lead to stress incontinence.

Overactive bladder, also known as urge incontinence, is the involuntary loss of urine preceded by a strong urge to void regardless of whether the bladder is full. Urge incontinence results from bladder contractions that overwhelm the ability of the cerebral centers to inhibit them. This bladder oversensitivity may originate from the bladder epithelium or detrusor muscle as the result of altered neural activation in the voiding cycle.

Overflow incontinence is urine loss associated with overdistension of the bladder, typically caused by an underactive detrusor muscle, outlet obstruction, or both. Patients may have frequent or constant dribbling, overactive bladder, or stress incontinence. Causes of detrusor muscle underactivity are outlined later in this chapter. Overflow incontinence is relatively uncommon but is more common in men because of the prevalence of obstructive prostate gland enlargement.

The first goal of the evaluation of urinary incontinence is to identify reversible causes of incontinence so that effective treatments may be instituted. The second goal is to identify conditions that may necessitate special evaluation or referral to a urologist or urogynecologist. Once transient causes and indications for specialty evaluation or referral have been excluded, the third goal is to decide whether the patient’s symptoms are more suggestive of urge incontinence or stress incontinence. After this has been determined, treatment may be initiated accordingly. If the treatment is ineffective, specialty evaluation may be indicated.

Indications for specialty evaluation or referral that are detected from history include recent onset within 2 months of urge incontinence or irritative bladder symptoms, previous surgery for incontinence, previous radical pelvic surgery, or incontinence associated with recurrent symptomatic urinary infections. Physical findings that usually necessitate specialty referral include gross pelvic prolapse and neurologic abnormalities suggestive of a systemic disorder or spinal cord lesion. Hematuria without infection and significant persistent proteinuria on urinalysis necessitate additional evaluation. Other situations that may necessitate specialty evaluation or referral are an abnormal postvoid residual volume, treatment failure, consideration of surgical intervention, or an inability to establish a presumptive diagnosis and treatment plan.

Key Historical Features

✓ Frequency of episodes

✓ Degree of bother to the patient

✓ Leakage of urine

• With coughing, laughing, lifting, or sneezing

• In association with a strong urge to urinate

• Without the patient’s being aware of the leakage

✓ Use of pad to protect clothing from leaking urine

✓ Time of day or night

✓ Relation to medication treatments

✓ Fluid intake

✓ Voiding habits

✓ How often sleep is interrupted by the need to urinate

✓ Presence of dysuria

✓ Sensation of incomplete bladder emptying

✓ Frequency of bowel movements

✓ Splinting of the vagina or perineum during defecation

✓ Presence of fecal incontinence

✓ Medical history

• Chronic lung disease

• Cognitive impairment

• Fecal impaction

• Lumbar disk disease

✓ Obstetric and gynecologic history

• Gravity and parity

• Number of vaginal, instrument-assisted, and cesarean deliveries

• Estrogen status

• Time interval between deliveries

• Hysterectomy, vaginal surgery

• Bladder surgery

• Pelvic trauma

• Pelvic radiotherapy

✓ Surgical history

✓ Medications

Key Physical Findings

✓ General examination for mobility status

✓ Neurologic examination for cognitive status, upper motor neuron lesions such as multiple sclerosis or Parkinson disease, lower motor neuron lesions such as sacral-nerve root lesions; assessment of lumbosacral nerve roots by checking deep tendon reflexes, lower extremity strength, and sharp or dull sensation

✓ Cardiovascular and pulmonary examination to assess for causes of cough

✓ Abdominal examination for masses, diastasis recti abdominis, ascites, or organomegaly

✓ Pelvic examination for pelvic masses, organ prolapse, or vaginal atrophy (the levator ani muscle function can be evaluated by asking the patient to tighten her vaginal muscles and hold the contraction as long as possible); evaluation of the bulbocavernous and clitoral sacral reflexes; and evaluation for inflammation, infection, and atrophy

✓ Rectal examination to evaluate for sphincter tone, fecal impaction, rectal lesions, or the presence of occult blood

✓ Extremity examination for peripheral edema

✓ Urine leakage should be assessed with coughing or Valsalva maneuver in both the supine and standing position

Suggested Work-Up

Urinalysis	To evaluate for urinary tract infection or diabetes-induced glycosuria
Urine culture	Not routinely indicated but possibly useful in identifying the causative organism of infections and in guiding antibiotic therapy
Assessment of postvoid residual volume by catheterization or ultrasonography	To detect urinary retention (<50 mL is normal; >200 mL is abnormal).
Cystometry	To measure bladder pressure during filling, which provides information about bladder capacity and the ability to inhibit detrusor contractions
Cystoscopy	Indicated for the evaluation of patients with incontinence who also have any of the following: hematuria or pyuria; irritative voiding symptoms such as frequency, urgency, and urge incontinence in the absence of reversible causes; bladder pain; recurrent cystitis; and suburethral mass
	Also indicated when urodynamic testing fails to duplicate symptoms of urinary incontinence

Additional Work-Up

Cystometric testing	Indicated as part of the evaluation of more complex disorders of bladder filling and voiding, such as the presence of neurologic disease and other comorbid conditions (there is only limited data suggestive of its need in the routine evaluation of women with urinary incontinence)
Urodynamic testing	May be indicated when surgical treatment of stress incontinence is planned
Pressure-flow voiding studies, uroflowmetry, and electromyography of the anal sphincter	May be indicated for the assessment of complex and neurogenic causes of urinary incontinence and voiding disorders

FURTHER READING

Culligan PJ, Heit M. Urinary incontinence in women: evaluation and management. Am Fam Physician. 2000;62:2433-2444.

Morantz CA. ACOG guidelines on urinary incontinence in women. Am Fam Physician. 2005;72:175.

Norton P, Brubaker L. Urinary incontinence in women. Lancet. 2006;367:57-67.

Wein AJ, Rackley RR. Overactive bladder: a better understanding of pathophysiology, diagnosis, and management. J Urol. 2006;175:S5-S10.

Weiss BD. Diagnostic evaluation of urinary incontinence in geriatric patients. Am Fam Physician. 1998;57:2675-2684.

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