Urinary Incontinence: Bypass, Overflow

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Chapter 61 Urinary Incontinence: Bypass, Overflow

INTRODUCTION

Description: Urinary incontinence is a sign, a symptom, and a disease all at the same time. Bypass incontinence is continuous incontinence occurring when the normal continence mechanism is bypassed, as with fistulae. Symptoms may be intermittent or continuous, making the establishment of a diagnosis difficult in some patients. Overflow incontinence is continuous or intermittent insensible loss of small volumes of urine resulting from an overfilled or atonic bladder.
Prevalence: Of all women who have hysterectomies, 0.05% develop a fistula and subsequent bypass incontinence. Overflow incontinence is uncommon and generally follows trauma, instrumentation, surgery, or anesthesia.
Predominant Age: Mid-reproductive age and onward. Overflow incontinence is more common in later years.
Genetics: No genetic pattern.

ETIOLOGY AND PATHOGENESIS

Causes: Bypass incontinence—fistulae may result from surgical or obstetric trauma, irradiation, or malignancy, although the most common cause by far (in developed countries) is unrecognized surgical trauma (obstructed labor in other parts of the world). Roughly 75% of fistulae occur after abdominal hysterectomy. Signs of a urinary fistula (watery discharge) usually occur from 5 to 30 days after surgery, although they may be present in the immediate postoperative period.
Overflow incontinence—trauma (vulvar, perineal, radical pelvic surgery), irritation/infection (chronic cystitis, herpetic vulvitis, herpes zoster), anesthesia (spinal, epidural, caudal), pressure (uterine leiomyomata, pregnancy), anatomic defect (cystocele, retroversion, or prolapse of the uterus), neurologic disorder (multiple sclerosis, diabetes, spinal cord tumors, herniated disc, stroke, amyloid disease, pernicious anemia, Guillain-Barré syndrome, neurosyphilis), systemic disease (hypothyroidism, uremia), medications (antihistamines, appetite suppressants, β-adrenergic agents, parasympathetic blockers, vincristine, carbamazepine), radiation therapy, behavioral problems (psychogenic, infrequent voiding).
Risk Factors: Bypass incontinence—surgery or radiation treatment. Most common after uncomplicated hysterectomy, although pelvic adhesive disease, endometriosis, or pelvic tumors increase the individual risk. Overflow incontinence—none known other than causes listed previously.

CLINICAL CHARACTERISTICS

Signs and Symptoms

Bypass Incontinence

• Continuous loss of urine (often from the vagina or rectum)
• Fistulae from the vagina to the bladder (vesicovaginal), urethra (urethrovaginal), or ureter (ureterovaginal). (Rarely, communication between the bladder and the uterus [vesicouterine] may also occur through the same mechanisms. Multiple fistulae are present in up to 15% of patients.)

Overflow Incontinence

• Frequent loss of small volumes of urine (may or may not be related to increases in intraabdominal pressure)
• Midline lower abdominal mass (with or without tenderness) that disappears with catheterization
• Ability for spontaneous voiding may or may not be compromised

DIAGNOSTIC APPROACH

Differential Diagnosis

Bypass Incontinence

• Overflow incontinence
• Urge incontinence
• Ectopic ureter

Overflow Incontinence

• Other forms of incontinence (stress, bypass/fistula)
• Chronic urinary tract infections
• Urinary tract obstruction
• Neurologic conditions presenting as an adynamic bladder

Associated Conditions: Vulvitis, vaginitis.

Workup and Evaluation

Laboratory: No evaluation indicated. Urinalysis is generally recommended, although results are nonspecific. Abrupt-onset incontinence in older patients should suggest infection, which may be confirmed through urinalysis or culture.
Imaging: Ureterovaginal fistulae should be evaluated by excretory urography to evaluate possible ureteral dilation or obstruction. Retrograde urography, with the passage of ureteral stents, may also be required. Ultrasonography demonstrates a distended bladder in patients with overflow incontinence.
Special Tests: If a vesicovaginal fistula is found, cystoscopy is required to evaluate the location of the fistula in relation to the ureteral opening and bladder trigone. For those with overflow incontinence that is either recurrent or unrelated to an obvious cause, urodynamics testing (including a cystometrogram) should be considered.
Diagnostic Procedures: When a fistula is suspected, the installation of a dilute solution of methylene blue (or sterile milk) into the bladder while a tampon is in place in the vagina documents a vesicovaginal fistula. A ureterovaginal fistula may be documented in a similar fashion using intravenous indigo carmine. For patients with overflow incontinence, physical examination and catheter drainage of the bladder are diagnostic. Urodynamics testing (cystometrogram) generally confirms the diagnosis.

Pathologic Findings

Based on cause. A distended, often hypotonic bladder is typical of patients with overflow incontinence.

MANAGEMENT AND THERAPY

Nonpharmacologic

General Measures: Bypass incontinence—urinary diversion, protection of the vulva from continuous moisture (zinc oxide, diaper rash preparations). Overflow incontinence—treatment of urinary tract infection (if present).
Specific Measures: Bypass incontinence—vesicovaginal fistulae that occur in the immediate postoperative period should be treated by large-caliber transurethral catheter drainage. Spontaneous healing is evident within 2 to 4 weeks. Similarly, in patients with a ureterovaginal fistula, prompt placement of a ureteral stent, left in place for 2 weeks, allows spontaneous healing for roughly 25% of patients. Surgical repair of genitourinary fistulae is generally delayed 2 to 4 months to allow complete healing of the original insult. In all cases, successful surgical repair consists of meticulous dissection of the fistulous tract and careful reapproximation of tissues. Overflow incontinence—prompt and continuous drainage if retention is present, timed voiding to reduce bladder volume, suprapubic pressure or Crede maneuver to reduce residual volume.
Diet: No specific dietary changes indicated.
Activity: No restriction.
Patient Education: Reassurance; American College of Obstetricians and Gynecologists Patient Education Pamphlet AP081 (Urinary Incontinence).

Drug(s) of Choice

Bypass incontinence—none.
Overflow incontinence—pharmacologic therapy for these patients is often unsatisfactory and many require long-term catheter drainage or intermittent self-catheterization to manage their problem.
Urinary tract antibiotics if infection is present.
Acetylcholine-like drugs (bethanechol chloride [Urecholine] 10 to 50 mg three to four times per day; may also be given as 2.5 to 5 mg SC).
Contraindications: Overflow incontinence—Hyperthyroidism, peptic ulcer, latent or active bronchial asthma, pronounced bradycardia or hypotension, vasomotor instability, coronary artery disease, epilepsy, or Parkinsonism.
Precautions: Overflow incontinence—it is preferred that bethanechol be given when the stomach is empty (1 hour before or 2 hours after meals). The sterile solution must not be given IM or IV. Bethanechol should not be given if the integrity of either the bladder wall or the gastrointestinal tract is in question or may be mechanically obstructed.

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Interactions: Overflow incontinence—bethanechol should be used with extreme care in patients receiving ganglion-blocking compounds.
Alternate Therapies: Overflow incontinence—intermittent self-catheterization, electrical stimulation, reduction cystoplasty, urinary diversion.

FOLLOW-UP

Patient Monitoring: Normal health maintenance. Patients are at increased risk for urinary tract infections, vaginitis, and vulvitis. Patients who have experienced overflow incontinence have an increased risk of recurrence.
Prevention/Avoidance: Careful surgical technique should be used to reduce the risk of fistula formation. Surveillance in situations that predispose to retention (e.g., after regional anesthesia, childbirth).
Possible Complications: Social isolation and vulvar and perineal irritation are common complications of any type of urinary incontinence. Ascending urinary tract infection (including pyelonephritis) may occur if a fistula or bladder distention is present.
Expected Outcome: Recurrence after surgical repair of a fistula is common, especially in patients who have undergone radiation therapy for malignancies. For patients with time-limited causes for overflow incontinence, a complete resolution with drainage should be expected. For patients with idiopathic retention or retention caused by chronic causation, frequent recurrence, possible dependence on self-catheterization, urinary diversion, and electrical stimulation are possible.

MISCELLANEOUS

Pregnancy Considerations: No effect on pregnancy, although pregnancy (and vaginal delivery) increases the risk of urinary retention and overflow incontinence. Obstructed labor is a major cause of vesicovaginal fistula in developing countries.
ICD-9-CM Codes: Bypass incontinence—788.30, 788.37 (Continuous leakage); overflow incontinence—788.39, 788.21 (Incomplete bladder emptying), 788.37 (Continuous leakage of urine), 788.34 (Without sensory awareness).

REFERENCES

Level II

Freeman RM. The role of pelvic floor muscle training in urinary incontinence. BJOG. 2004;111:37.

Level III

Abrams P, Blaivas JG, Stanton SL, Andersen JT. The standardization of terminology of lower urinary tract function produced by the International Continence Society Committee on Standardization of Terminology. Scand J Urol Nephrol. 1988;114:5.

American College of Obstetricians and Gynecologists. Genitourinary tract changes. Obstet Gynecol. 2004;104:56S.

American College of Obstetricians and Gynecologists. Urinary incontinence in women. Obstet Gynecol. 2005;105:1533.

Consensus Conference. Urinary incontinence in adults. JAMA. 1989;261:2685.

Diaz-Ball FL, Moore CA. A diagnostic aid for vesicovaginal fistula. J Urol. 1969;102:424.

Dubeau CE. The aging lower urinary tract. J Urol. 2006;175:S11.

Katz VL. Postoperative counseling and management. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, editors. Comprehensive Gynecology. 5th ed. Philadelphia: Mosby/Elsevier; 2007:681.

Lentz GM. Urogynecology. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, editors. Comprehensive Gynecology. 5th ed. Philadelphia: Mosby/Elsevier; 2007:561.

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

Norton PA. Urinary incontinence. Clin Obstet Gynecol. 1990;33:293.

Sims JM. On the treatment of vesico-vaginal fistula. Am J Med Sci. 1852;23:59.

Smith PP, McCrery RJ, Appell RA. Current trends in the evaluation and management of female urinary incontinence. CMAJ. 2006;175:1233.

Sutherland SE, Goldman HB. Treatment options for female urinary incontinence. Med Clin North Am. 2004;88:345.

Symmonds RE. Incontinence: Vesical and urethral fistulas. Clin Obstet Gynecol. 1984;27:499.

Urinary Incontinence Guideline Panel. Urinary incontinence in adults: Clinical Practice Guidelines. Rockville, MD: Agency for Health Care Policy and Research, U.S. Dept of Health and Human Services, 1992. AHCPR publication 92–0038.

Wall LL. Obstetric vesicovaginal fistula as an international public-health problem. Lancet. 2006;368:1201.

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