Differential diagnosis of urinary incontinence.

Some degree of bladder instability is common in elderly people because aging changes in the portion of the frontal cortex concerned with micturition allow uninhibited bladder contractions. Although this in itself is not a cause of urinary incontinence, it may be an important predisposing factor and must be differentiated from all other causes. Stress incontinence occurs when the bladder outlet becomes incompetent because of weakness of the supporting pelvic muscles. Incontinence also can be a symptom of atrophic urethritis, acute cystitis, chronic bacteriuria, or bladder carcinoma. Overflow incontinence results from retention of urine, which can be caused by impacted feces, prostatic enlargement, autonomic neuropathy, or anticholinergic drugs. A complete history and thorough physical examination, with special attention to neurologic signs, vulval appearance, and rectal examination often will reveal the cause of urinary incontinence. If the cause is not readily apparent, cystometrography is indicated, and if the bladder is normal, cystoscopy should be done immediately. A more limited examination is acceptable only in demented patients who may not be able to cooperate in the examination and subsequent treatment.