The Chlamydia IgG test is a confidential blood test that checks for "memory" (IgG) antibodies, which signal a past exposure to the Chlamydia bacteria. It is important to understand: this test does not detect a current, active infection (for that, your doctor will order a PCR/NAAT test). This test is a vital part of a comprehensive health screen, especially for an infertility workup, as a past, untreated infection can be a silent cause of fertility challenges. A simple blood draw provides this important, confidential insight into your past health history, guiding your long-term health plan.