Urethritis

Urethritis is inflammation of the urethra, the tube that carries urine out of the body. It is most often caused by sexually transmitted infections, especially Chlamydia trachomatis and Neisseria gonorrhoeae. Other causes include Mycoplasma genitalium, Trichomonas, herpes simplex virus and, less often, irritation from soaps or injury. Symptoms include burning or pain when passing urine, discharge from the penis or vagina, and itching. Many people, especially women, have no symptoms. Untreated, infections can spread and cause problems such as pelvic inflammatory disease, epididymitis and infertility.

Lab tests linked to urethritis:

• Leukocyte esterase, urine: a dipstick test for white cells. A positive first-catch urine result supports urethritis, but can also be positive with a urinary tract infection.
• Doctors test for chlamydia and gonorrhea with a nucleic acid amplification test (NAAT) on urine or swabs. They may add tests for Mycoplasma genitalium and Trichomonas, a Gram stain of discharge, and tests for HIV and syphilis.

How results are read:

• A positive NAAT for chlamydia or gonorrhea confirms the cause. Partners need testing and treatment too.
• A positive leukocyte esterase or white cells under the microscope, with negative chlamydia and gonorrhea tests, points to other causes such as Mycoplasma genitalium.
• A urine culture helps tell a urinary tract infection apart from urethritis.

When to see a doctor:

• See a doctor about pain when passing urine, a new discharge, or if a partner has an STI.
• Get prompt assessment for testicular swelling, pelvic pain, fever or joint pain with urinary symptoms. Sudden severe testicular pain needs emergency assessment to rule out torsion.

Clinical takeaway: urethritis is diagnosed from symptoms with NAAT testing for STIs, and a positive leukocyte esterase supports inflammation but doesn't identify the cause.