Understanding Lab Tests for Past CMV Infection
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Cytomegalovirus (CMV) is a common virus that belongs to the herpes virus family. Most people who become infected with CMV show no symptoms, but the body develops lifelong immunity. Determining whether someone has had a past CMV infection is important for certain medical situations, including pregnancy planning and immunocompromised patients.
Recommended Test
Cytomegalovirus (CMV) Antibodies, IgG
This test measures CMV IgG antibodies in the blood, which indicate past infection with cytomegalovirus. The presence of CMV IgG antibodies, particularly when CMV IgM antibodies are absent, confirms that a person has been previously infected and typically has lifelong immunity. These antibodies remain detectable in the blood indefinitely after initial infection.
2907 reviews
How Blood Tests Detect Past CMV Infection
When the body encounters CMV, it produces specific antibodies to fight the infection. These antibodies remain in the bloodstream long after the infection has resolved, serving as markers that indicate previous exposure to the virus. Blood testing can accurately identify these antibodies to determine immunity status.
Understanding Your Results
A positive CMV IgG test result indicates that you have been exposed to CMV in the past and have developed immunity. This information can be particularly valuable for pregnant women, as it helps assess the risk of primary CMV infection during pregnancy, or for individuals with compromised immune systems who need to understand their infection history.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for proper interpretation of test results and medical guidance.
