Urinary Incontinence: Bypass and Overflow

Introduction

• Description: Urinary incontinence is a sign, symptom, and disease all at the same time. Bypass incontinence is continuous incontinence that occurs when 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 the 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 (up to 10% after radical hysterectomy). Overflow incontinence is uncommon and generally develops after trauma, instrumentation, surgery, or anesthesia.

• Predominant Age: Mid-reproductive age and older. 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 (in the developing world), 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). Approximately 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. Erosion of surgically placed mesh may not occur until a month after surgery.

• 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, overcorrection of the urethra from surgery), neurologic disorder (multiple sclerosis, diabetes, spinal cord tumors, herniated disc, stroke, amyloid disease, pernicious anemia, Guillain-Barré syndrome, neurosyphilis, alcoholism), systemic disease (diabetes mellitus, hypothyroidism, uremia), medications (antihistamines, appetite suppressants, β-adrenergic agents, parasympathetic blockers, vincristine, carbamazepine), radiotherapy, 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 previously listed.

Signs and Symptoms

Diagnostic Approach