Bladder outlet obstruction Health Article

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.

Alternative Names

BOO; Lower urinary tract obstruction; Prostatism

Causes, incidence, and risk factors

Bladder outlet obstruction can have many different causes, including:

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

Less common causes of bladder outlet obstruction include:

• Cystocele
• Foreign objects
• Posterior urethral valves (congenital birth defect)
• Urethral spasms
• Urethral diverticula

Bladder outlet obstruction 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.

See also:

• Benign prostatic hypertrophy
• Bladder stones
• Obstructive nephropathy
• Reflux nephropathy

Symptoms

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)

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 reveal kidney damage
• Cystoscopy and retrograde urethrogram (x-ray to look for urethral narrowing)
• Ultrasound to locate the blockage of urine, and find out how well the bladder empties
• Urinalysis to look for blood or infection
• Urine culture to show an infection
• Uroflowmetry to determine how fast the urine flows out
• Urodynamic testing to see how much the urine flow is blocked and how well the bladder contracts