The prevalence of urinary incontinence appears to increase gradually during young adult life, has a broad peak around middle age, and then steadily increases in the elderly. Urinary incontinence has been shown to affect women’s social, clinical, and psychologic well-being. It is esti-mated that less than one half of all incontinent women seek medical care, even though the condition can often be treated.
Several types of urinary incontinence have been identified, and a patient may have more than one type (Table 28.1).
The normal voiding “reflex” is initiated when stretch receptors within the detrusor muscle, the layer of mus-cle that lines the interior bladder wall, send a signal to the brain. The brain then decides if it is socially acceptable to void. The detrusor muscle contracts, elevating the blad-der pressure to exceed the urethral pressure. The external urethral sphincter, under voluntary control, relaxes, and voiding is completed.
Normally, the detrusor muscle allows the bladder to fill in a low-resistance setting. The volume increases within the bladder, but the pressure within the bladder remains low. Patients with an overactive detrusor muscle have uninhibited detrusor contractions. These contractions cause a rise in the bladder pressure that overrides the ure-thral pressure, and the patient will leak urine without evi-dence of increased intra-abdominal pressure. Idiopathic detrusor overactivity has no organic cause, but has a neuro-genic component.
A patient with detrusor overactivity presents with the feel-ing that she must run to the bathroom frequently and urgently. This may or may not be associated with nocturia. These symptoms may occur after bladder surgery to correct stress incontinence or after extensive bladder dissection during pelvic surgery.
Normal physiology and anatomy allow for increased abdominal pressure to be transmitted along the entire urethra. In addition, the endopelvic fascia that extends beneath the urethra allows for the urethra to be com-pressed against the endopelvic fascia, thus maintaining a closed system and maintaining the bladder neck in a stable position. In patients with stress incontinence, increased intra-abdominal pressure is transmitted to the bladder, but not to the urethra (specifically, the urethral–vesical junction [UVJ]), due to loss of integrity of the endopelvic fascia. The bladder neck descends, the bladder pressure is elevated above the intra-urethral pressure, and urine is lost. Patientswith stress incontinence present with loss of urine during activities that cause increased intra-abdominal pressure, such as coughing, laughing, or sneezing.
Some patients may have symptoms of both urge incontinence and stress incontinence. These patients experience urine leakageduring coughing, laughing, or sneezing; the increased intra-abdominal pressure that occurs during these activi-ties causes the UVJ to descend and also stimulates the detrusor to contract. This clinical scenario may be treated as stress or as detrusor instability, although it is not clear which approach offers a better outcome.
In this form of incontinence, the bladder does not empty completely during voiding due to an inability of the detru-sor muscle to contract. This may occur because of an obstruction of the urethra or a neurologic deficit that causes the patient to lose the ability to perceive the need to void. Urine leaks out of the bladder when the bladder pressure exceeds the urethral pressure. These patients expe-rience continuous leakage of small amounts of urine.
Patients with urinary incontinence should undergo a basic evaluation that includes a history, physical examination, direct observation of urine loss, measurement of postvoid residual volume, urine culture, and urinalysis. These tests and examinations are performed to rule out urinary tract infection, neuromuscular disorders, and pelvic support defects, all of which are associated with urinary inconti-nence. The patient should also be asked about her fluid intake, the relationship of her symptoms to fluid intake and activity, and medications. A voiding diary may be helpful in this evaluation process.
Urodynamic testing may also be useful. These tests measure the pressure and volume of the bladder as it fills and the flow rate as it empties. In single-channel uro-dynamic testing, the patient voids, and the volume isrecorded. A urinary catheter is then placed and the postvoid residual (PVR) urine is recorded. The bladder is filled in a retrograde fashion. The patient is asked to note the first sensation that her bladder is being filled. She then is asked to note when she has a desire to void, and when she can no longer hold her urine. Normal values are: 100–150 cc for first sensation, 250 cc for first desire to void, and 500–600 cc for maximum capacity. In multichannel urodynamictesting, a transducer is placed in the vagina or rectum tomeasure intra-abdominal pressure. A transducer is placed in the bladder, and EMG pads are placed along the per-ineum. This form of testing provides an assessment of the entire pelvic floor, and an uninhibited bladder contraction can be clearly documented.
Cystourethroscopy may be used in the evaluation ofurinary incontinence. In this procedure, a slender, lighted scope is introduced into the bladder. Cystourethroscopy can help to identify bladder lesions and foreign bodies, as well as urethral diverticula, fistulas, urethral strictures, and intrinsic sphincter deficiency. It frequently is used as part of the surgical procedures to treat incontinence.
There are many options for treatment. Often, treatments are more effective when used in combination.
Lifestyle interventions that may help modify incontinence include weight loss, caffeine reduction and fluid manage-ment, reduction of physical forces (e.g., work, exercise), ces-sation of smoking, and relief of constipation. Pelvic muscle training (Kegel exercises) can be extremely effective in treat-ing some forms of incontinence, especially stress inconti-nence. The exercises work to strengthen the pelvic floor and thus decrease the degree of urethral hypermobility. The patient is instructed to repeatedly tighten her pelvic floor muscles as though she were voluntarily stopping a urine stream. Biofeedback techniques and weighted vaginal cones are available to assist patients in learning the proper tech-nique. When performed correctly, these exercises have success ratesof about 85%. Success is defined as a decreased number ofepisodes of incontinence. However, once the patient stops the exercise regimen, she will revert to her original status. Other treatments for stress incontinence include various pessaries and continence tampons that can be placed vagi-nally to aid in urethral compression.
Behavioral training is aimed at increasing the patient’s bladder control and capacity by gradually increasing the amount of time between voids. This type of training is most often used to treat urge incontinence, but may also be successful in treating stress incontinence and mixed incontinence. It may be augmented by biofeedback.
A number of other pharmacologic agents appear to be effective for treating frequency, urgency, and urge incontinence. However, the response to treatment often is unpredictable, and side effects are common with effective doses. Generally, drugs improve detrusor overactivity by inhibiting the con-tractile activity of the bladder. These agents can be broadly classified into anticholinergic agents, tricyclic antidepres-sants, musculotropic drugs, and a variety of less commonly used drugs
Many surgical treatments have been developed for stress urinary incontinence, but only a few—retropubic colpo-suspension and sling procedures—have survived andevolved with enough supporting evidence to make recom-mendations (Figs. 28.4 A and B). The aim of retropubic colposuspension is to suspend and stabilize the anterior vaginal wall and, thus, the bladder neck and proximal urethra, in a retropubic position. This prevents their descent and allows for urethral compression against a sta-ble suburethral layer. In the Burch procedure, which can be performed abdominally or laparoscopically, two or three nonabsorbable sutures are placed on each side of the mid-urethra and bladder neck. Another procedure uses tension-free tape placed at the midurethra to raise the urethra back into place. This procedure can be done through the vagina. The success of tension-free vaginal tape has led to the introduction of similar products with modified methods of midurethral sling placement (retropubic “top-down” and transobturator). Bulking agents, such as collagen, carbon-coated beads, and fat, are used for the treatment of urody-namic stress incontinence with intrinsic sphincter deficiency (Fig. 28.4C). They are injected transurethrally or peri-urethrally in the periurethral tissue around the bladder neck and proximal urethra. They provide a “washer” effect around the proximal urethra and the bladder neck. These agents usually are used as second-line therapy after surgery has failed, when stress incontinence persists with a non-mobile bladder neck, or among older, debilitated women for whom any form of operative treatment may be hazardous.
Success rates vary depending on the skill of the surgeon and the technique used. Tension-free vaginal tape and the Burch suspension have success rate at five years of 85%. Preoperative counseling should include not only the risks of the pro-cedures, but also the goals. The patient must understand thatthe procedure may not allow her to be completely continent, as overcorrection (making the sling too tight) may lead to urinary retention. In addition, studies only show 5-year data; thus, surgery should not be presented as a permanent solu-tion. One study of women who underwent Burch colposuspensionfound that the cure rate of stress incontinence gradually decreased over 10–12 years, reaching a plateau at 69%. Approximately10% of patients required at least one additional surgery to cure their stress incontinence.