The prostate is a gland of the male reproductive system that is located in front of the rectum and just below the bladder. The prostate is small and weighs about 15 to 25 grams. It is about the same size and shape as a walnut. The prostate is wrapped around a tube called the urethra, which carries urine from the bladder out through the tip of the penis.
The prostate is made up largely of muscular and glandular tissues. Its main function is to produce fluid for semen, which transports sperm. During the male orgasm (climax), muscular contractions squeeze the prostate's fluid into the urethra. Sperm, which are produced in the testicles, are also propelled into the urethra during orgasm. The sperm-containing semen leaves the penis during ejaculation.
Although not technically part of the urinary system, the prostate gland is important to the urinary health. That's because the prostate surrounds the top portion of the tube that carries urine from the bladder (the urethra). Normally, the location of the prostate gland isn't a problem. But infection or inflammation can cause the gland to swell, squeezing the urethra and affecting the ability to urinate. That's exactly what happens in prostatitis, although the cause of the inflammation depends on the type of prostatitis.
Risk factors include bladder outlet obstruction (e.g., stone, tumor, BPH), diabetes mellitus, a suppressed immune system, and urethral catheterization (i.e., small tube inserted into the bladder through the urethra to drain urine). Some sexually transmitted diseases (STDs; e.g., non-gonnococcal urethritis, gonorrhea) increase the risk for developing bacterial prostatitis. Unprotected anal and vaginal intercourse can allow bacteria to enter the urethra and travel to the prostate.
Bacterial prostatitis is caused by the growth of bacteria that are normally found in prostatic fluid, such as Escherichia coli and Klebsiella. Approximately 80% of organisms causing ABP are aerobic gram-negative organisms (e.g., Escherichia coli, Enterobacter, Serratia, Pseudomonas, Enterococcus, and Proteus species). Urine that flows back into the urethra (urine reflux) that enters the prostate can also cause the condition.
Sometimes bacteria remain in the prostate following acute prostatitis. Catheter tubes used to drain the urinary bladder, trauma to the urinary system or infections in other parts of the body can sometimes be the source of the bacteria.
Heavy lifting: Lifting heavy objects when the bladder is full may cause urine to back up into the prostate.
Certain occupations: Occupations that subject the prostate to strong vibrations, such as driving a truck or operating heavy machinery, may play a role. Though biking is a good exercise for the rest of the body, it may irritate the prostate gland.
Structural abnormalities of the urinary tract: Narrowing (stricture) of the urethra may elevate pressure during urination and cause symptoms. Sometimes prostatitis is caused by a sexually transmitted organism, such as Chlamydia. However, most cases are caused by infections that are not sexually ransmitted. These infections can't be passed on to sexual partners.
The acute form of prostatitis is the least common, but is also the most severe. Symptoms are often sudden, and the condition may require hospitalization. Symptoms of chronic prostatitis tend to develop more slowly and aren't as severe as those of acute prostatitis.
Symptoms of acute bacterial prostatitis (ABP) include the following:
Symptoms of chronic bacterial prostatitis (CBP) and nonbacterial prostatitis are generally less severe than those of ABP and include the following:
Chronic nonbacterial prostatitis is the most common form, yet it's also the least well understood. Researchers aren't even sure of the cause.
In general, the signs and symptoms of nonbacterial prostatitis are similar to those of chronic bacterial prostatitis, although fever is generally absent. The major difference, however, is that tests won't detect any bacteria in the urine or in fluid from the prostate gland. But there may be white blood cells in the urine and semen.
Patients with prostatodynia have symptoms of prostatitis but there is no evidence of infection or inflammation.