Laboratory tests — including tests of blood and other body fluids or tests of tissue samples — can detect CMV virus.

Screening and testing for your baby

If you're pregnant, testing to determine whether you've ever been infected with CMV can be important. Pregnant women with antibodies have a very small chance of a reactivation infecting their unborn child.

If your doctor detects a new CMV infection during pregnancy, a prenatal test (amniocentesis) can determine if the fetus has the infection. In amniocentesis your doctor obtains and examines a sample of amniotic fluid. Amniocentesis is generally recommended when abnormalities that might be caused by CMV are seen on ultrasound.

If your doctor suspects your baby has congenital CMV, it's important to test the baby within the first three weeks of birth. After that, tests can't show your baby has congenital CMV because the baby might have contracted the infection by nursing or exposure to other people with the virus. If your baby has CMV, your doctor likely will recommend additional tests to check the health of the baby's organs, such as the liver and kidneys.

Screening and testing if you have weakened immunity

Testing for CMV can also be important if you have a weakened immune system. For example, if you have HIV or AIDS, carrying the CMV virus means you'll need regular monitoring for complications of CMV, such as vision and hearing problems.