A case-referent study on fetal bacteremia and late fetal death of unknown etiology in Lithuania.

BACKGROUND: The objectives were to test the hypothesis that certain strains of microorganisms are present in fetal blood in a significant proportion of parturient women suffering unexplained third trimester fetal death, and to examine the correlation between fetal bacteremia and histologic chorioamnionitis and vasculitis.
METHODS: A case-referent study was carried out on 58 pregnant women with fetal death of unknown etiology (cases) and 116 pregnant women at term (referents) with live fetuses. Cultures from maternal endocervix, amniotic fluid, placental homogenate, external ear and blood of newborns were performed in both groups. Histological examination of placentas and fetal membranes was carried out in order to identify chorioamnionitis and chorionic vasculitis.
RESULTS: Intrauterine fetal bacteremia was observed in 36% of cases and in 0% of referents (p= 0.001). Escherichia coli was the most common strain, isolated in 21% of fetal blood samples in cases. Extensive histologic chorioamnionitis was observed in 50% of cases with the presence of Escherichia coli in blood of stillborns. Chorionic vasculitis was found in 67% of such cases. Positive significant correlations between isolation of the Escherichia coli from maternal endocervix, amniotic fluid, placenta, fetal ear and blood in stillborns and histological chorioamnionitis and chorionic vasculitis were observed.
CONCLUSIONS: Escherichia coli bacteremia was detected in a significant proportion of stillborns suffering a third trimester prelabor death. Fetal bacteremia significantly correlated with histologic signs of inflammation in placenta and membranes. Ascending subclinical intrauterine infection may play an important role in the etiology of otherwise unexplained late prelabor fetal death.