(See also Overview of Voiding.)
Urinary retention is incomplete emptying of the bladder or cessation of urination; it may be
Causes include impaired bladder contractility, bladder outlet obstruction, detrusor-sphincter dyssynergia (lack of coordination between bladder contraction and sphincter relaxation), or a combination.
Retention is most common among men, in whom prostate abnormalities or urethral strictures cause outlet obstruction. In either sex, retention may be due to drugs (particularly those with anticholinergic effects, including many OTC drugs), severe fecal impaction (which increases pressure on the bladder trigone), or neurogenic bladder in patients with diabetes, multiple sclerosis, Parkinson disease, or prior pelvic surgery resulting in bladder denervation.
Urinary retention can be asymptomatic or cause urinary frequency, a sense of incomplete emptying, and urge or overflow incontinence. It may cause abdominal distention and pain. When retention develops slowly, pain may be absent. Long-standing retention predisposes to UTI and can increase bladder pressure, causing obstructive uropathy.
Diagnosis is obvious in patients who cannot void. In those who can void, incomplete bladder emptying is diagnosed by postvoid catheterization or ultrasonography showing an elevated residual urine volume. A volume < 50 mL is normal; < 100 mL is usually acceptable in patients > 65 but abnormal in younger patients. Other tests (eg, urinalysis, blood tests, ultrasonography, urodynamic testing, cystoscopy, cystography) are done based on clinical findings.
Relief of acute urinary retention requires urethral catheterization. Subsequent treatment depends on cause. In men with benign prostatic hypertrophy, drugs (usually alpha-adrenergic blockers or 5-alpha-reductase inhibitors) or surgery may help decrease bladder outlet resistance.
No treatment is effective for impaired bladder contractility; however, reducing outlet resistance with alpha-adrenergic blockers may increase bladder emptying.
Intermittent self-catheterization or indwelling catheterization is often required. An indwelling suprapubic tube or urinary diversion is a last resort.