The Chlamydia IgG test is a blood test that detects the presence of IgG antibodies to Chlamydia trachomatis, a sexually transmitted bacteria that can cause a range of infections including urethritis, cervicitis, and pelvic inflammatory disease. IgG antibodies are produced by the immune system in response to a Chlamydia trachomatis infection and may remain in the blood for an extended period, even after the infection has been treated. The test may be used to diagnose a current or past infection, determine if an individual has been exposed to the bacteria, or screen individuals who are at risk of infection. The test is typically performed on a blood sample and sent to a laboratory for analysis. Results are reported as a numerical value or a positive/negative result, depending on the laboratory’s reference range. The Chlamydia IgG test is not the primary test for Chlamydia infection, and other tests, such as nucleic acid amplification tests (NAATs), are more commonly used.