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Chlamydia Testing

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Formal name: Chlamydia trachomatis Culture; Chlamydia trachomatis DNA Probe; Chlamydia trachomatis by Amplified Detection; Chlamydia trachomatis by Direct Antigen Detection (DFA)
Related tests: Gonorrhea Testing

The Test Sample

What is being tested?

This test is looking for evidence of infection by the bacterium Chlamydia trachomatis. Chlamydia is the most common bacterial sexually transmitted disease (STD) in the United States and is especially common among people 15 to 25 years of age. The Centers for Disease Control and Prevention (CDC) estimates that 2.8 million Americans are infected with chlamydia each year and notes that women are frequently re-infected if their partners don't get treatment. Actual incidence may be higher since many people do not experience any symptoms and their cases go undiagnosed and unreported. Still, over one million new cases are reported each year. Diagnosing and treating chlamydia is very important to prevent long-term complications and spread of the infection to others.

Chlamydia is generally transmitted through sexual contact (oral, vaginal, or anal) with an infected partner. Risk factors include having multiple sex partners, coinfection or previous infection with another STD, and not using barrier contraception consistently. An infected mother can pass the infection to her baby during childbirth. These babies are in danger of developing conjunctivitis, an inflammation that can threaten eyesight, and pneumonia.

About 75% of infected women and 50% of infected men have no symptoms; some may experience only mild symptoms. For women, symptoms, if they occur, include bleeding between menstrual periods and after sexual intercourse, abdominal pain, painful intercourse, and an abnormal vaginal discharge. For men, symptoms include pus or milky discharge from the penis and inflammation of the prostate (prostatitis) or of the rectal area (proctitis). Both sexes can experience painful or frequent urination.

Chlamydia is easily treated with a course of antibiotics, but if left untreated, it can cause severe reproductive and other health problems. If left untreated, women may develop pelvic inflammatory disease (PID) from infections that start on the cervix but that can spread to the fallopian tubes and ovaries. This can cause infertility and increase the risk of tubal (ectopic) pregnancy, which is often fatal. Women who are infected and pregnant may experience heavy bleeding before delivery and premature rupture of the membranes. Men may become sterile. Both sexes may develop rectal itching and red, swollen, itchy eyes.

How is the sample collected for testing?

Many different kinds of samples may be used for testing, but not all laboratories can test every kind of sample. A health practitioner may use a swab or brush to collect a sample of cells or secretion from the infected area, such as the urethra, penis, anus, throat, cervix or vagina. Sometimes a vaginal sample may be collected with a swab by the woman who is undergoing testing (self-collection). A first-catch urine sample may be collected in a container provided by the health practitioner or laboratory.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

Tell your health care provider about use of antibiotics or, if you are a woman, douches or vaginal creams within 24 hours before testing vaginal samples, as they may affect test results. You may be instructed to wait one to two hours after you last urinated before collecting a urine sample. Follow any instructions you are given.