Urethritis is infection of the urethra, the tube that carries urine from the bladder out of the body.
Urethritis may be caused by bacteria, fungi, or viruses (for example, herpes simplex virus). In most women, the bacteria involved are those that normally live in the lower intestine. These bacteria reach the urethra from the anus. Men are much less likely to develop urethritis because the opening of the male urethra is far removed from the anus, and thus bacteria from the anus less often reach the urethra. Bladder infection (cystitis) develops in most women who have urethritis but not in most men who have urethritis.
Sexually transmitted organisms—such as Neisseria gonorrhoeae, which causes gonorrhea—can spread to the urethra during sexual intercourse with an infected partner (see Sexually Transmitted Diseases: Gonorrhea). Chlamydia and the herpes simplex virus are also commonly transmitted sexually and can cause urethritis (see Sexually Transmitted Diseases: Chlamydial and Other Infections). When men develop urethritis, the gonorrheal organism is a very common cause. Although this organism may infect the urethra in women, the vagina, cervix, uterus, ovaries, and fallopian tubes are more likely to be infected. Trichomonas, a type of microscopic parasite, also causes urethritis in men. Urethritis may also be caused by the bacteria that commonly cause other urinary tract infections, such as Escherichia coli.
In both men and women, there is usually pain with urination and a frequent, urgent need to urinate. Sometimes people have no symptoms. In men, when gonorrhea or chlamydia is the cause, there is usually a discharge from the urethra. The discharge is often yellowish green when the gonococcal organism is involved and may be clear when other organisms are involved. In women, discharge is less common.
Other disorders that cause pain with urination include bladder infection and vaginitis. In vaginitis, urination may cause pain because urine, which is acidic, irritates the inflamed vulva and lining of the vagina.
Infections of the urethra that are not treated or are inadequately treated eventually can cause a narrowing (stricture) of the urethra. A stricture increases the risk that infections will develop in the bladder or the kidneys. Untreated gonorrhea occasionally leads to an accumulation of pus (abscess) around the urethra. An abscess can cause outpouchings from the urethral wall (urethral diverticula), which can also become infected. If the abscess perforates the skin, the vagina, or the rectum, urine may flow through a newly created abnormal connection (urethral fistula).
Doctors can usually make a diagnosis of urethritis based on the symptoms and examination. A sample of the discharge, if present, is collected by inserting a soft-tipped swab into the end of the urethra. The urethral swab is then sent to a laboratory for analysis so that the infecting organism can be identified.
Prevention and Treatment
Sexually transmitted diseases that cause urethritis may be prevented by using a condom.
Treatment depends on the cause of the infection. However, identification of the organism causing urethritis can take days. Thus, doctors usually begin treatment with antibiotics that cure the most common causes. For sexually active men, treatment is usually with a ceftriaxone injection for gonorrhea plus oral azithromycin or oral doxycycline for chlamydia. If tests exclude the possibility of gonorrhea and chlamydia, trimethoprim/sulfamethoxazole or a fluoroquinolone antibiotic (such as ciprofloxacin) may be used. Women are treated as if they had cystitis (see Urinary Tract Infections (UTI): Bladder Infection (Cystitis)). An antiviral drug, such as acyclovir, may be needed for a herpes simplex infection.
Last full review/revision September 2007 by Stewart Shankel, MD