Overview

Prostate gland

The prostate is a walnut-sized gland that makes up part of the male reproductive system. The prostate gland makes some of the milky fluid (semen) that carries sperm. It is located in front of the rectum and just below the bladder, where urine is stored. The prostate gland surrounds the urethra, the canal through which urine passes out of the body. During a man's orgasm (sexual climax), muscles squeeze the prostate's fluid into the urethra. Sperm, which are made in the testicles, also go into the urethra during orgasm. The milky fluid carries the sperm through the penis during orgasm.

Prostate gland enlargement

It is common for the prostate gland to enlarge as men age. The enlargement of the prostate gland is called benign prostatic hyperplasia, or BPH. Most enlargements are NOT due to cancer.

Though the prostate continues to grow during most of a man's life, the enlargement doesn't usually cause problems before age 40. However, more than half of men in their 60s and as many as 90 percent in their 70s and 80s have some symptoms of BPH, according to the National Institutes of Health.

As the prostate enlarges, the layer of tissue surrounding it stops it from expanding, causing the prostate to press against the urethra. This causes the wall of the bladder to thicken and become irritated. The bladder begins to contract even when it contains small amounts of urine, causing more frequent urination.

Eventually, the bladder weakens and loses the ability to empty itself completely, so urine remains in the bladder. The narrowing of the urethra makes the urine stream weak and leads to straining in an attempt to empty the bladder. The most common cause of difficulty with urination in men is enlargement of the prostate gland.

More on Benign Prostatic Hyperplasia

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This article was reviewed and updated June 2007.