Diagnosis of Congenital Rubella Maternal serum rubella titers Viral detection in the mother via culture and / or reverse transcriptase-polymerase chain reaction (RT-PCR) of amniotic fluid, nose, throat (preferred), urine, cerebrospinal fluid (CSF), or blood specimens Infant antibody titers (measured serially) and viral detection as above Pregnant women routinely have a serum rubella IgG titer measured early in pregnancy.