Test Details: This test looks for antibodies to cytomegalovirus (CMV), a virus in the herpes family, in the patient's blood. CMV can spread through exchange of bodily fluids, such as saliva, blood, urine, breast milk and semen. The virus usually causes only a mild illness. But it can do serious harm to unborn children, people with HIV/AIDS, or others with weak immune systems. The CMV IgG antibody test is performed to diagnose acute CMV infection, or if the person has had the infection in their lifetime.