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:
- 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.
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
Cystoscopyand retrograde urethrogram (x-ray) to look for narrowing of the urethra
- Tests to determine how fast urine flows out of the body (
- 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
Urinalysisto look for blood or signs of infection in the urine
- Urine culture to check for an infection
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.
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.