Christopher M. Tarnay, MD, & Narender N. Bhatia, MD
Urinary loss due to abnormal anatomic variations is uncommon but extremely important to consider in the evaluation of the incontinent woman. Bypass incontinence may often mimic other forms of urinary incontinence but usually presents as constant dribbling or dampness. Patients may complain of positional loss of urine without urge or forewarning. Diagnosing this type of incontinence requires a high level of suspicion and an understanding of the underlying anatomic deviation in the lower urinary tract. Genitourinary fistulas (vesicovaginal or ureterovaginal) can be a debilitating cause of incontinence and are formed because of poor wound healing after a traumatic insult (eg, obstetric laceration, pelvic surgery, perineal trauma, or radiation exposure).
Leakage due to fistulas is generally continuous, although it may be elicited by position change or stress-inducing activities. Evaluation should include a careful examination of the vaginal walls for fistulas. This can be facilitated by filling the bladder with milk or dilute indigo carmine dye and looking for pooling in the vaginal canal. Pad testing can be performed by having the patient ingest 200 mg of oral phenazopyridine hydrochloride (Pyridium) several hours before a subsequent examination. By placing a tampon in the vagina and on the perineum, the diagnosis may be confirmed by inspection of the pads after a period of time. Further imaging (intravenous urography) and cystoscopy can identify the exact location of the aberrant communication. If diagnosis is made early, the fistulous tract may heal with prolonged catheterization. However, if this procedure is unsuccessful or if diagnosis is made late, surgical correction is generally the only hope for cure.
Another important but uncommon cause of involuntary urine loss is urethral diverticula. Diverticula are essentially weaknesses or "hernias" in the supportive fascial layer of the bladder or urethra. Urethral diverticulum is most likely to cause symptoms of urinary loss. It has an incidence of 0.3-3% in women and is thought to be largely an acquired condition resulting from obstruction and expansion of the paraurethral Skene's glands. The symptoms of constant small amounts of leakage or urethral discharge are often described. A suburethral mass is visible and palpable on physical examination. Urine or discharge may often be "milked" by palpation of the suburethral mass. Treatment is usually surgical excision of the diverticulum.
Functional and transient incontinence
Incontinence may be caused by factors outside the lower urinary tract and is particularly significant in the geriatric population, because often a multitude of special circumstances affect the health of the elderly. Physical impairment, cognitive function, medication, systemic illness, and bowel function are all factors that may contribute to incontinence. Many immobile patients are incontinent because of the inability to toilet. Cognitive disturbances limit a patient's ability to respond normally to the sensation to void. Numerous medications have effects on the bladder that may reduce capacity, inhibit bladder function, increase diuresis and bladder load, or relax the urinary sphincter. Additionally, stool impaction and constipation both have been associated with increased prevalence of urinary incontinence. Treatments should first identify the etiologic factors of the incontinence and then reduce or remove the cause.