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Chlamydia Testing

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Also known as: Chlamydia NAAT or NAT; Chlamydia/GC STD Panel
Formal name: Chlamydia trachomatis by Nucleic Acid Amplification Test (NAAT); Chlamydia trachomatis Culture; Chlamydia trachomatis DNA Probe

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The Test Sample

What is being tested?

Chlamydia is one of the most common bacterial sexually transmitted diseases (STD) in the United States and can cause serious complications if not treated. Chlamydia testing identifies the bacteria Chlamydia trachomatis as the cause of a person's infection. Screening for, diagnosing, and treating chlamydia is very important in preventing long-term complications and spread of the infection to others.

Chlamydia infections are especially common among people 15 to 24 years of age. The Centers for Disease Control and Prevention (CDC) estimates that 2.86 million Americans are infected with chlamydia each year and notes that women are frequently re-infected if their partners don't get treatment. The actual number of cases may be higher since many people do not experience any symptoms and do not get tested and diagnosed. Still, over one million new cases are reported each year.

Chlamydia is generally spread 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 a condom correctly and consistently.

Many people with chlamydia infections have no symptoms and some may experience only mild symptoms. Signs and symptoms of chlamydia are similar to and can be confused with those cause by another STD, gonorrhea, so tests for these infections are often done at the same time. (For more, see "The Test" tab.)

Chlamydia is easily treated with a course of antibiotics. If not diagnosed and treated, it can cause severe reproductive and other health problems.

In women, untreated chlamydia infections can lead to pelvic inflammatory disease (PID) from infections that start on the cervix but spread to the fallopian tubes and ovaries. This can cause:

Pregnant women who are infected may experience heavy bleeding before delivery and premature rupture of the membranes and/or have babies with low birth weights. Infected mothers can pass the infection to their baby during childbirth. These babies are at risk of developing complications such as pneumonia or conjunctivitis, an inflammation that, left untreated, can threaten eyesight.

Rarely, men who are not treated may become infertile.

How is the sample collected for testing?

For women, vaginal swabs are the optimal sample for genital chlamydia testing. A healthcare practitioner may use a swab or small brush to collect a sample of cells or secretion from the vagina during a pelvic examination. Sometimes, a vaginal sample is collected by the woman who is undergoing testing (self-collection).

Urine is recommended for men, but can also be used for women. As you begin to urinate, collect the initial portion of your urine stream (first-catch) in a container provided by the healthcare practitioner or laboratory.

Sometimes, a healthcare practitioner may use a swab or brush to collect a sample of cells or secretion from other areas that may be infected, such as the urethra, penis, anus, or throat.

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 the healthcare practitioner about any use of antibiotics or, if you are a woman, douches or vaginal creams. You may be asked to avoid using these within 24 hours before testing vaginal samples since they may affect test results. Menstruation will not affect 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.