Bladder Outlet Obstruction


What is bladder outlet obstruction (BOO)?

Bladder outlet obstruction (BOO) occurs when there is a blockage at the base or neck of the bladder. Such a blockage reduces or stops the flow of urine into the urethra, which carries urine from the body. BOO is most common in older men and often is linked to prostate problems. More men than women have BOO.

Symptoms and Causes

What causes bladder outlet obstruction (BOO)?

The causes of bladder outlet obstruction include:

  • Scar tissue in the urethra.
  • Bladder stones.
  • An enlarged prostate gland.
  • Prostate cancer.
  • Tumors in the rectum, uterus or cervix.

What are the symptoms of bladder outlet obstruction (BOO)?

You may have BOO if you:

  • Have pain when passing urine.
  • Have trouble starting your urine stream.
  • Feel like you have a full bladder but cannot empty completely.
  • Feel like some urine remains in your bladder after voiding.
  • Pass urine frequently during sleeping hours.
  • Have pain in your abdomen.
  • Have urine flow that starts and stops.
  • Have a urinary stream that is slow.
  • Void often with small urine volume.

Diagnosis and Tests

How is bladder outlet obstruction (BOO) diagnosed?

BOO may be suspected if there is abnormal abdominal growth or a larger than normal bladder. Also, men with an enlarged prostate gland or women with cystocele (prolapsed bladder) can be diagnosed with BOO.

Tests may include:

  • Blood tests to check for kidney damage.
  • Urine cultures to test for infection.
  • Ultrasound of the kidneys and bladder to find where the urine blockage is occurring.
  • Urine testing to look for blood in the urine.
  • X-rays to look for narrowing of the urethra.

Management and Treatment

How is bladder outlet obstruction (BOO) treated?

BOO is treated in line with the cause of the problem. A thin, flexible tube (catheter) is inserted through the urethra into the bladder, in most cases. The placement of the catheter can relieve the blockage.

In some cases, a tube is placed into the bladder through the belly area. This tube, called a suprapubic catheter, will drain the bladder.

For the long-term care of BOO, medical treatments for the various diseases causing BOO are available. In some cases, however, the long-term treatment of BOO requires surgery.

The timely treatment of the disease can reduce problems. If BOO is not diagnosed right away, bladder and kidney problems are more likely to develop.

Last reviewed by a Cleveland Clinic medical professional on 02/22/2017.


  • Bladder Outlet Obstruction: Etiology and Evaluation ( Accessed 3/6/2013
  • Bladder Prolapse (Cystocele/Fallen Bladder) ( Accessed 3/6/2013

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy