Prostatitis is swelling of the prostate gland. The prostate is a walnut-sized gland in men that surrounds the urethra. It produces a fluid that is part of semen.

Anatomy of the Prostate Gland
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There are four types of prostatitis:

  • Acute bacterial prostatitis
  • Chronic bacterial prostatitis
  • Chronic pelvic pain syndrome
  • Asymptomatic inflammatory prostatitis

Acute and chronic bacterial prostatitis are caused by an infection. A bacteria enters the prostate—usually from the urinary tract or rectum.

The causes of chronic pelvic pain syndrome and asymptomatic inflammatory prostatitis are not clearly understood. In some people, it is possible that a cause may not be found.