Bladder outlet obstruction (BOO) is a blockage at the base of the bladder. It reduces or stops the flow of urine into the urethra. The urethra is the tube that carries urine out of the body.
This condition is common in aging men. It is often caused by enlarged prostate. Bladder stones and bladder cancer are also more commonly seen in men than women. As a man ages, his chance of getting these diseases increases greatly.
Other common causes of BOO include:
- Pelvic tumors (cervix, prostate, uterus, rectum)
- Narrowing of the tube that carries urine out of the body from the bladder (urethra), due to scar tissue or certain birth defects
Less common causes include:
- Cystocele (when the bladder falls into the vagina)
- Foreign objects
- Urethral spasms
- Inguinal (groin) hernia
The symptoms of BOO may vary, but can include:
Exams and Tests
Your health care provider will ask about your symptoms and medical history. You will undergo a physical exam.
One or more of the following problems may be found:
- 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 of BOO depends on its cause. A tube, called a catheter, is inserted into the bladder. The insertion is done through the urethra to relieve the blockage.
Sometimes, a catheter placed through the belly area into the bladder is needed to drain the bladder.
Most often, you will need surgery for long-term cure of BOO. However, many of the diseases that cause this problem can be treated with medicines. Talk to your provider about possible treatments.
Most causes of BOO can be cured if diagnosed early. However, permanent damage to the bladder or kidneys can result if the diagnosis is delayed.
When to Contact a Medical Professional
Call your provider if you have symptoms of BOO. Early diagnosis can often lead to a simple and effective cure.
BOO; Lower urinary tract obstruction; Prostatism; Urinary retention - BOO
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Boone TB, Stewart JN. Additional therapies for storage and emptying failure. In: Wein AJ, Kavoussi LR, Partin AW, Peters CA, eds. Campbell-Walsh Urology. 11th ed. Philadelphia, PA: Elsevier; 2016:chap 87.
McNicholas TA, Speakman MJ, Kirby RS. Evaluation and nonsurgical management of benign prostatic hyperplasia. In: Wein AJ, Kavoussi LR, Partin AW, Peters CA, eds. Campbell-Walsh Urology. 11th ed. Philadelphia, PA: Elsevier; 2016:chap 104.
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Review Date 5/23/2016
Updated by: Jennifer Sobol, DO, urologist with the Michigan Institute of Urology, West Bloomfield, MI. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.