Diagnosis of Congenital Toxoplasmosis Serial IgG measurement (for maternal infection) Amniotic fluid polymerase chain reaction (PCR) testing (for fetal infection) Serologic testing, brain imaging, cerebrospinal fluid (CSF) analysis, ophthalmologic evaluation (for neonatal infection), and PCR testing of various body fluids or tissues Serologic testing is important in diagnosing maternal and congenital infection.