Serum or plasma mass concentration of immunoglobulin G (IgG) antibodies against cytomegalovirus (CMV)

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have a weakened immune system (such as due to HIV/AIDS, chemotherapy, or organ transplant) and want to check for CMV antibodies. It can also be used before certain procedures (like bone marrow or stem cell transplants) to ensure safety. In pregnant women, it may be used to evaluate potential CMV exposure in the fetus.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. The test is quick and typically done in a lab setting. If you’re pregnant or have a history of bleeding disorders, let your provider know before the test.

What the Results Mean

Results are qualitative (positive or negative) and indicate whether you have detectable CMV antibodies. A positive result suggests past infection and immunity, while a negative result means no detectable antibodies, which could mean you’ve never been exposed or the test was taken too soon after exposure.

Possible Causes of Abnormal Results

A positive result is generally reassuring for people with weakened immune systems, as it suggests immunity from prior infection. However, if you’re immunocompromised and test negative, you may still be at risk for CMV infection. A negative result in someone who has never been tested before may warrant further evaluation for recent exposure.