Urinary retention is incomplete emptying of the bladder or cessation of urination.
Urinary retention may be:
Acute
Chronic
Causes include impaired bladder contractility, bladder outlet obstruction, detrusor-sphincter dyssynergia (lack of coordination between bladder contraction and sphincter relaxation), or a combination. (See also Overview of Voiding.)
Retention is most common among men, in whom prostate abnormalities or urethral strictures cause outlet obstruction. In either sex, retention may be due to medications (particularly those with anticholinergic effects, including many over-the-counter medications), 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 may 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 urinary tract infections and can increase bladder pressure, causing obstructive uropathy.
Diagnosis of Urinary Retention
Measurement of postvoid residual volume
Diagnosis is obvious in patients who cannot void. In those who can void, incomplete bladder emptying is diagnosed by postvoid catheterization or ultrasound showing an elevated residual urine volume. A volume < 50 mL is normal; < 100 mL is usually acceptable in patients > 65 years but abnormal in younger patients. Other tests (eg, urinalysis, blood tests, ultrasound urodynamic testing, cystoscopy, cystography) are done based on clinical findings.
Treatment of Urinary Retention
Urethral catheterization and treatment of cause
Sometimes sacral neuromodulation in non-obstructive urinary retention
Relief of acute urinary retention requires urethral catheterization. Subsequent treatment depends on cause. In men with benign prostatic hyperplasia, medications (usually alpha-adrenergic blockers or 5-alpha-reductase inhibitors) or surgery may help decrease bladder outlet resistance.
No treatment is consistently effective for impaired bladder contractility; however, reducing outlet resistance with alpha-adrenergic blockers may improve bladder emptying. Sacral neuromodulation is a minimally invasive therapy based upon electrical stimulation of the S3 and S4 nerve roots that can restore volitional voiding in patients with non-obstructive urinary retention (1). Although the exact mechanism is unknown, sacral neuromodulation appears to work by blocking inappropriate urethral afferent signals that can suppress normal bladder contractions.
Intermittent self-catheterization or indwelling catheterization is often required. An indwelling suprapubic tube or urinary diversion is a last resort.
Treatment reference
1. Tilborghs S, De Wachter S. Sacral neuromodulation for the treatment of overactive bladder: systematic review and future prospects. Expert Rev Med Devices. 2022;19(2):161-187. doi:10.1080/17434440.2022.2032655
Key Points
Mechanisms include impaired bladder contractility, bladder outlet obstruction, and detrusor-sphincter dyssynergia.
Incomplete retention is diagnosed by a postvoid residual volume > 50 mL (> 100 mL in patients > 65 years).
Prescribe urethral catheterization and treat the cause of retention.
