Chlamydia tests use a sample of body fluid or urine to see whether
chlamydia bacteria (Chlamydia trachomatis) are present
and causing an infection.
Chlamydia is the most common bacterial
sexually transmitted infection (STI) in the United
Several types of tests can be used to find a chlamydia
infection. Most tests use a sample of body fluid from the affected area.
Nucleic acid amplification tests (NAAT). These tests find the genetic material (DNA) of chlamydia bacteria. These tests are very good at identifying chlamydia. A test that is positive almost always
means the problem is there and is unlikely to be a false-positive test result. A polymerase chain
reaction (PCR) test is an example of a nucleic acid amplification test. This
test can also be done on a urine sample.
Nucleic acid hybridization tests (DNA probe test). A probe test also finds
chlamydia DNA. A probe test is very accurate but is not as sensitive as nucleic
acid amplification tests.
Enzyme-linked immunosorbent assay (ELISA, EIA). This quick test finds substances (chlamydia
antigens) that trigger the immune system to fight
Direct fluorescent antibody test (DFA). This quick test also finds chlamydia
Chlamydia culture. A culture is a
special cup that allows the chlamydia bacteria to grow. Results take longer (5 to 7 days) than the other tests. The
culture must be done in a lab.
Why It Is Done
A test for chlamydia is done to:
See whether symptoms of a sexually transmitted
infection (STI) are caused by a chlamydia infection.
women in the first trimester and again in the third trimester if high-risk
sexual behaviors are reported. Treating a pregnant woman who has a chlamydia
infection can prevent an infection in her newborn.
Check for infection in a newborn whose mother had
a chlamydia infection at the time of delivery.
How To Prepare
A chlamydia test is done on either a urine sample or fluid
(direct sample) collected from the area of the body that is most likely to be
infected. If your chlamydia test is being done on
Urine sample: Do not urinate for 2 hours
before a urine sample is collected.
Direct sample (usually from the cervix): A
woman should not douche or use vaginal creams or medicines for 24 hours before
having a chlamydia test.
How It Is Done
If a urine sample is collected for
nucleic acid amplification testing (such as PCR testing), do not urinate for 2
hours before the test. Do not wipe the genital area clean before urinating.
Collect the first part of your urine stream, immediately as you begin
In a direct sample, a sample of body
fluid is taken from the affected area. In adults, these areas may include the
urethra, vagina, rectum, or eye.
For men. To collect a
sample from the urethra or rectum, your doctor will insert a swab into the
opening of your urethra or rectum. A sample from the
urethra is more likely to detect chlamydia if a man has not urinated for at
least 2 hours before the sample is taken.
For women. To collect a sample from the cervix, you will take off your
clothes below the waist and drape a cloth around your waist. You will lie on
your back on an exam table with your feet raised and supported by stirrups.
This allows your doctor to examine your vagina and genital area. Your doctor
will insert a lubricated speculum into your vagina. The
speculum gently spreads apart the vaginal walls so the inside of the vagina and
the cervix can be looked at. Samples are collected from the cervix with a swab
or small brush.
To collect a sample from your eye, your doctor will
gently brush the insides of your lower and upper eyelids with a swab.
There is also a self-test for women to collect a sample from their vagina and bring it to the lab for testing.
In rare cases, a throat culture may be done.
How It Feels
There is no discomfort in collecting a urine sample.
Collecting a sample of fluid from the
urethra, anus, or rectum may cause mild discomfort or pain.
Collecting a sample from the cervix may cause mild discomfort. Most women
find that the procedure feels like a Pap test or pelvic exam. Some women feel
some cramping when the speculum is inside the vagina.
sample from the eye is painless unless the eyelids have sores on them.
There is no chance for problems in collecting a urine sample.
There is very little chance of problems when
collecting a sample of fluid from the cervix, urethra, rectum, eyes, or
In rare cases, a person may suddenly get dizzy or feel
vasovagal syncope) because of fear or pain when the
swab is inserted into the urethra.
Chlamydia tests use a sample of body fluid
or urine to see whether chlamydia bacteria (Chlamydia trachomatis) are present and causing an infection.
DNA are found. If a culture is done, no chlamydia
bacteria grow in the culture. More tests for other sexually transmitted
infections (STIs) may be needed to find the cause of symptoms.
Chlamydia antigens or DNA are
found. If a culture is done, chlamydia bacteria grow in the
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
the rectal sample.
Using antibiotics before the test.
What To Think About
If a chlamydia infection is suspected, do not
have sexual intercourse until the test results have come back. If you have a
chlamydia infection, do not have sexual intercourse for 7 days after the start
of treatment. Your sex partner(s) should also be treated for a chlamydia infection
so that you don't get reinfected and so that others don't get
Only one laboratory test (NAAT, ELISA, DFA, DNA probe
testing, or chlamydia culture) is needed to diagnose chlamydia. Your doctor can
choose which test to use.
Your doctor is required to report your
chlamydia test result to the state health department. The department may contact
your sex partners to inform them that they also need treatment.
Screening for and treating chlamydia can help prevent
pelvic inflammatory disease (PID). To learn more about the treatment of a chlamydia infection, see the topic
Other sexually transmitted
infections may be present at the same time as chlamydia. So it is important to be
tested and treated for all STIs. Chlamydia as well as other STIs can also
increase the chance of getting
human immunodeficiency virus (HIV). An HIV test may be
offered at the same time as a test for chlamydia or other STIs.
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
How this information was developed to help you make better health decisions.