Diagnosis

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

During pregnancy and after delivery

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

If your doctor detects a new CMV infection while you're pregnant, a prenatal test (amniocentesis) can determine whether the fetus has been infected. In this test, your doctor takes 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. 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.

In people who 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, or if you've had a transplant, your doctor may want to monitor you regularly.