At a Glance
Why Get Tested?
To screen for or diagnose a chlamydia infection
When to Get Tested?
For screening: may be recommended if you are sexually active, pregnant or considering pregnancy, or at increased risk for this sexually transmitted disease (STD)
For diagnosis: when you have symptoms of this STD, such as such as vaginal discharge and abdominal pain (for women) or unusual discharge from the penis or pain on urination (for men); when a newborn has conjunctivitis
A swab or brush of cells or secretion from the infected area or a first-catch urine sample
Test Preparation Needed?
Tell your doctor about use of antibiotics or, for women, 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.
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 doctor 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 doctor 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 doctor 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.
Ask a Laboratory Scientist
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Kimberly A. Workowski and Stuart Berman. Sexually Transmitted Diseases Guidelines, 2010. Morbidity and Mortality Weekly Report. PDF available for download at http://www.cdc.gov/std/treatment/2010/STD-Treatment-2010-RR5912.pdf through http://www.cdc.gov. Published December 27, 2010. Accessed July 2, 2012.
United States Preventive Service Task Force. USPSTF Recommendations for STI Screening. Available online at http://www.uspreventiveservicestaskforce.org/uspstf08/methods/stinfections.htm through http://www.uspreventiveservicestaskforce.org. Last updated March 2008. Accessed July 2, 2012.
Laboratory Procedure Manual. Centers for Disease Control and Prevention. PDF available for download at http://www.cdc.gov/nchs/data/nhanes/nhanes_05_06/chlmda_d_met_chlamydia.pdf through http://www.cdc.gov. Published October 2007. Accessed July 2, 2012.
Sexual Conditions Health Center: Chlamydia Tests. Medscape. Available online at http://www.webmd.com/sexual-conditions/chlamydia-tests?page=3 through http://www.webmd.com. Last Updated: December 15, 2010. Accessed Jul 2, 2012.
Centers for Disease Control and Prevention.Chlamydia - CDC Fact Sheet. Available online at http://www.cdc.gov/std/chlamydia/stdfact-chlamydia.htm through http://www.cdc.gov. Last updated February 8, 2012. Accessed July 2, 2012.
Centers for Disease Control and Prevention. Chlamydia and Gonorrhea — Two Most Commonly Reported Infectious Diseases in the United States. Available online at http://www.cdc.gov/Features/dsSTDData/ through http://www.cdc.gov. Last updated April 22, 2011. Accessed July 2, 2012.
Centers for Disease Control and Prevention. 2010 Treatment Guidelines, Special Populations. Available online at http://www.cdc.gov/std/treatment/2010/specialpops.htm#msm through http://www.cdc.gov. Accessed September 2012.
(January 13, 2009) Association for Public Health Laboratories. Expert Consultation Meeting Summary Report, Laboratory Diagnostic Testing for Chlamydia trachomatis and Neisseria gonorrhoeae. PDF available for download at http://www.aphl.org/aphlprograms/infectious/std/Documents/CTGCLabGuidelinesMeetingReport.pdf through http://www.aphl.org. Accessed Sept 2012.
Sources Used in Previous Reviews
Centers for Disease Control and Prevention. Chlamydia Fact Sheet. Available online at http://www.cdc.gov/std/Chlamydia/STDFact-Chlamydia.htm through http://www.cdc.gov.
Arnot Ogden Medical Center. Chlamydia. Available online at http://www.aomc.org/chlamydia.html through http://www.aomc.org.
American Social Health Association. Learn Chlamydia Facts. Available online at http://www.ashastd.org/learn/learn_chlamydia_facts.cfm through http://www.ashastd.org.
Centers for Disease Control and Prevention. Sexually transitted diseases treatment guidelines 2002. MMWR 2002;51 (No. RR-6) [32-41].
Planned Parenthood. Chlamydia. Available online at http://www.plannedparenthood.org/health-topics/stds-hiv-safer-sex/chlamydia-4266.htm through http://www.plannedparenthood.org. Accessed February 2009.
Centers for Disease Control and Prevention. Chlamydia - CDC Fact Sheet. Available online at http://www.cdc.gov/std/Chlamydia/STDFact-Chlamydia.htm through http://www.cdc.gov. Accessed February 2009.
TeensHealth. Chlamydia. Available online at http://kidshealth.org/teen/sexual_health/stds/std_chlamydia.html through http://kidshealth.org. Accessed February 2009.
ARUP Consult. Sexually Transmitted Infections, Bacteria. Available online at http://www.arupconsult.com/Topics/InfectiousDz/Bacteria/STIs.html# through http://www.arupconsult.com. Accessed February 2009.
WebMD. Chlamydia Tests. Available online at http://www.webmd.com/sexual-conditions/chlamydia-tests through http://www.webmd.com. Accessed February 2009.