Healthcare providers test for chlamydia in one of two ways:
- Swab: A swab is taken of the urethra (men), cervix (women), and/or rectum (for people who have receptive anal sex). For women, the cervical swab is taken as part of a pelvic exam done with a speculum.
- Urine: Many providers will also use a urine test to diagnose chlamydia in men. Although a urine test can be performed in women, it is slightly less sensitive than a cervical swab and so is less often used. Recent studies, however, suggest that urine testing may actually be a reasonably effective way to diagnose chlamydia in women in settings where a pelvic exam is impractical - and doctors are not comfortable allowing women to take their own swabs.
Once a sample has been acquired, it is sent to a laboratory for testing. Depending on the sample and the lab, testing may involve growing chlamydia from the sample, looking for chlamydial DNA, or using antibodies to identify whether or not the sample contains any organisms.
Fun Fact: Urine tests are highly effective in men because the site of infection is the urethra. Therefore, urine passes through the infection site where it can collect bacteria. In women, the site of infection is the usually the cervix, and so infection may be harder to detect.
Source: Cook RL, Hutchison SL, Østergaard L, Braithwaite RS, Ness RB. "Systematic review: noninvasive testing for Chlamydia trachomatis and Neisseria gonorrhoeae." Ann Intern Med. 2005 Jun 7;142(11):914-25.