Bladder outlet obstruction

Alternative names

BOO; Lower urinary tract obstruction; Prostatism

Definition

Bladder outlet obstruction occurs at the base of the bladder, and reduces or prevents the flow of urine into the urethra (the tube that carries urine out of the body).

Causes, incidence, and risk factors

Bladder outlet obstruction can have many different causes. Some of the most common causes of BOO are:

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

Less common causes of bladder outlet obstruction include:

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

Bladder outlet obstruction is most common in aging men, and 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. One in three American males over the age of 60 has significant symptoms of bladder outlet obstruction.

Symptoms

The symptoms of bladder outlet obstruction may vary. The most common symptoms experienced include:

• Slow urinary flow
  
• Delayed onset of urination (urinary hesitancy)
  
• Inability to urinate (acute urinary retention)
  
• Urinary stream starts and stops (urinary intermittency)
  
• Urinary tract infection
  
• Abdominal pain
  
• Pain on urination (dysuria)
  
• Frequent urination
  
• Continuous feeling of a full bladder
  

Signs and tests

If bladder outlet obstruction is suspected, your health care provider will take a thorough history of your problems and perform a physical exam. On physical exam, your provider may find one or more of the following possible causes: