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Bladder outlet obstruction

Definition

Bladder outlet obstruction (BOO) is a blockage at the base of the bladder that reduces or prevents the flow of urine into the urethra, the tube that carries urine out of the body.

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Alternative Names

BOO; Lower urinary tract obstruction; Prostatism

Causes, incidence, and risk factors

Bladder outlet obstruction (BOO) can have many different causes, including:

Benign prostatic hyperplasia (BPH), or enlarged prostate
Bladder stones
Bladder tumors (cancer)
Pelvic tumors (cervix, prostate, uterus, rectum)
Urethral stricture (scar tissue)

Less common causes include:

Cystocele (when the bladder falls into the vagina)
Foreign objects
Posterior urethral valves (birth defect in males)
Urethral spasms
Urethral diverticula

This condition is most common in aging men. It is often caused by BPH. Bladder stones and bladder cancer are also more commonly seen in men than women. As a man ages, his chance of developing these diseases increases dramatically.

Symptoms

The symptoms of bladder outlet obstruction may vary, but can include:

Abdominal pain
Continuous feeling of a full bladder
Frequent urination
Inability to urinate (acute urinary retention)
Pain during urination (dysuria)
Problems starting urination (urinary hesitancy)
Slow urine flow
Urinary tract infection
Urine stream starts and stops (urinary intermittency)
Waking up at night to urinate (nocturia)

Signs and tests

If bladder outlet obstruction is suspected, your health care provider will take a thorough history of your problems. During a physical exam, your provider may find one or more of the following possible causes:

Abdominal growth
Cystocele (women)
Enlarged bladder
Enlarged prostate (men)

Tests may include:

Blood chemistries to look for signs of kidney damage
Cystoscopy and retrograde urethrogram (x-ray) to look for narrowing of the urethra
Tests to determine how fast urine flows out of the body (uroflowmetry)
Tests to see how much the urine flow is blocked and how well the bladder contracts (urodynamic testing)
Ultrasound to locate the blockage of urine and find out how well the bladder empties
Urinalysis to look for blood or signs of infection in the urine
Urine culture to check for an infection

Treatment

Treatment of bladder outlet obstruction depends on the cause of the problem. For most cases, a tube called a catheter, inserted through the urethra into the bladder, will relieve the blockage.

Sometimes a suprapubic catheter (a tube placed through the belly area into the bladder) is needed to drain the bladder.

Long-term treatment of bladder outlet obstruction usually involves surgery. However, medical treatment options are available for many of the diseases that cause this problem. Discuss treatment options with your health care provider.

Expectations (prognosis)

If diagnosed early, most causes of bladder outlet obstruction can be successfully treated. However, if the diagnosis is delayed, permanent damage to the bladder or kidneys can result.

Calling your health care provider

If you have symptoms of bladder outlet obstruction, call your provider. Early diagnosis is important and can often lead to a simple and effective cure.

References

Zeidel ML. Obstructive uropathy. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 125.

McNicholas TA, Kirby RS, Lepor H. Evaluation and nonsurgical management of benign prostatic hyperplasia. In: Wein AJ, ed. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 92.

Andersson K, Wein AJ. Pharmacologic management of lower urinary tract storage and emptying failure. In: Wein AJ, ed. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 68.

Cespedes RD, Gerboc JL. Other therapies for storage and emptying failure. In: Wein AJ, ed. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 75.

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