Requirements for diagnosis of prenatal cytomegalovirus infection by amniotic fluid culture.

BACKGROUND: Amniotic fluid culture is considered to be the best method for the detection of antenatal cytomegalovirus (CMV) infection and prediction of congenital CMV infection. Recently, however, some false-negative results have been reported. OBJECTIVES: Prediction of congenital CMV infection by amniotic fluid culture with emphasis on false-negative results. STUDY DESIGN: Retrospective study of 42 pregnant women with primary CMV infection. First, estimation of seroconversion related to the gestational age was established. Afterwards, results of amniotic fluid culture were compared either with CMV isolation from biopsies from aborted fetuses, or with viral culture of newborns' urine. RESULTS: In 18 cases (43%), amniotic fluid culture gave negative results which coincided with 18 uninfected newborns. In 18 other cases (43%), amniotic fluid culture was positive for CMV: 7 newborns with CMV viruria and 11 terminations of pregnancy with CMV isolated from fetal biopsies. In the remaining 6 cases, amniotic fluid culture gave negative results, whereas the 6 newborns were all infected. CONCLUSION: Amniotic fluid culture remains an accurate method for the diagnosis of CMV antenatal infection. However, in order to avoid false-negative results, the importance of a correct estimation of the gestational age of seroconversion and of a sufficient interval between primary infection and amniocentesis are stressed.