Prenatal indicators of congenital cytomegalovirus infection

Objective: To assess the validity of a diagnostic protocol designed to pred ict the outcome of newborns of mothers suspected to have primary cytomegalo virus (CMV) infection during the first 4 months of pregnancy. Study design: Anti-CMV immunoglobulin (Ig) M detection by enzyme immunoassa y and immunoblot together with the determination of anti-CMV IgG avidity al lowed us to classify 456 women as (1) uninfected, (2) undergoing either a p rimary or a recurrent infection, or (3) having an undefined serologic condi tion. Prenatal diagnosis was carried out at 21 to 23 weeks' gestation for w omen. The presence of the virus in the amniotic fluid was determined by cul ture, polymerase chain reaction, and quantitative polymerase chain reaction , Macroscopic and histologic examinations were undertaken on tissue from ab orted fetuses, whereas for newborns culture was performed on urine sampled during the first week of life. Results: Congenital infections were found exclusively among women undergoin g a primary infection. The quantitative determination of CMV DNA in the amn iotic fluid of at least 10(3) genome equivalents gave a 100% certainty of d etecting an infected fetus. Higher viral loads were associated with fetuses or newborns with symptoms. Conclusions: IgM tests and the IgG avidity determination can identify all w omen at risk of transmitting CMV Furthermore, a high CMV DNA load in amniot ic fluid could be an indicator of symptomatic congenital infection at a rel atively early stage of pregnancy.