Bladder outlet obstruction
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.
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:
- Foreign objects
- Posterior urethral valves (congenital birth defect)
- 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, the chance of developing these diseases increases dramatically.
The symptoms of bladder outlet obstruction may vary, but can include:
- Abdominal pain
- Continuous feeling of a full bladder
- Delayed onset of urination (urinary hesitancy)
- Frequent urination
- Inability to urinate (acute urinary retention)
- Pain on urination (dysuria)
- 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 mass
- Cystocele (women)
- Distended 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
- Ultrasound to locate the blockage of urineand 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
- Uroflowmetry to determine how fast urine flows out of the body
- Urodynamic testing to see how much the urine flow is blocked and how well the bladder contracts
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 obstruction temporarily.
Occasionally, 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.
If diagnosed early, most causes of bladder outlet obstruction can be treated with great success. However, if diagnosis is delayed, permanent damage can result.
Long-term or high-grade bladder outlet obstruction can permanently damage all parts of the urinary system.
- Bladder and kidney stones
- Kidney failure
- Recurrent urinary tract infections
- Urinary incontinence
- Urinary retention
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.
The condition may be prevented by identifying and treating the cause of the blockage.
Wein AJ, ed. Campbell-Walsh Urology. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2007.
Tseng TY, Stoller ML. Obstructive uropathy. Clin Geriatr Med. 2009 Aug;25(3):437-43.
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Scott Miller, MD, Urologist in private practice in Atlanta, Georgia. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.