Bladder outlet obstruction (BOO) is a blockage at the base of the bladder. It reduces or prevents the flow of urine into the tube that carries urine out of the body (urethra).
Common causes of bladder outlet obstruction (BOO) include:
- 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 greatly.
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 that starts and stops (urinary intermittency)
- Waking up at night to urinate (nocturia)
- Nausea, fatigue, and fluid retention if kidney failure occurs
Exams and Tests
Your health care provider will ask about your symptoms and medical history and will do 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 bladder outlet obstruction depends on the cause of the problem. For most cases, a tube called a catheter is inserted through the urethra into the bladder. The catheter will relieve the blockage.
Sometimes a suprapubic catheter (a tube placed through the belly area into the bladder) is needed to drain the bladder.
Surgery is most often needed for long-term treatment of bladder outlet obstruction. However, many of the diseases that cause this problem can be treated with medicines. Talk to your health care provider about possible treatments.
Most causes of bladder outlet obstruction can be successfully treated 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 health care provider if you have symptoms of bladder outlet obstruction. Early diagnosis can often lead to a simple and effective cure.
BOO; Lower urinary tract obstruction; Prostatism
Zeidel ML. Obstructive uropathy. In: Goldman L, Schafer AI, eds. Goldman's 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.
Update Date 6/2/2014
Updated by: Scott Miller, MD, Urologist in private practice in Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.