Most men with prostatitis have chronic prostatitis/pelvic pain syndrome, inflammatory or noninflammatory. The cause of this type of prostatitis is not known. Few men with prostatitis have prostatitis associated with a bacterial infection.

Acute prostatitis and chronic bacterial prostatitis

Bacteria infecting the prostate cause acute prostatitis and chronic bacterial prostatitis. Bacteria most likely enter the prostate by:

• Traveling through the urethra.
• Being present in the urine because of a bladder infection.
• Being introduced through the use of a urinary catheter.

Chronic prostatitis/pelvic pain syndrome, inflammatory (nonbacterial prostatitis)

The specific cause of chronic prostatitis/pelvic pain syndrome, inflammatory, is usually not known. However, health professionals believe the possible causes include:

• Blocked urine flow.
• Abnormal movement of urine and prostate secretions into the prostate.
• Microorganisms that may infect the prostate. However, if they are present, they usually are not detectable in the urine.
• The immune system attacking the prostate (autoimmune disease).
• Chemicals normally found in the urine, such as uric acid, which may get into the prostate and cause irritation.
• Abnormal nerve or muscle function.

Chronic prostatitis/pelvic pain syndrome, noninflammatory (prostatodynia)

The causes of chronic prostatitis/pelvic pain syndrome, noninflammatory, may be the same as those for chronic prostatitis/pelvic pain syndrome, inflammatory. Some health professionals think that the prostate may not be involved at all but that a combination of factors, including nervous system problems, strained pelvic floor muscles, and emotional issues, cause the pain.