Bladder outlet obstruction

Alternative Names

BOO; Lower urinary tract obstruction; Prostatism

Definition of Bladder outlet obstruction

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.

Causes, incidence, and risk factors

Bladder outlet obstruction (BOO) can have many different causes, including:


The symptoms of bladder outlet obstruction may vary, but can include:

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:


Treatment of bladder outlet obstruction depends on the cause of the problem. For most cases, a tube, called a catheter, inserted through the urethra into the bladder, will relieve the obstruction temporarily.

Expectations (prognosis)

If diagnosed early, most causes of bladder outlet obstruction can be treated with great success. However, if diagnosis is delayed, permanent damage can result.


Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Scott Miller, MD, Urologist in private practice in Atlanta, Georgia. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 6/17/2010

Kidney anatomy
Female urinary tract
Male urinary tract
Kidney - blood and urine flow

ADAM Medical Encyclopedia

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