Spectrum of Changes Seen With Placental Intravascular Organisms

Fetal bacterial infections are a common cause of fetal/neonatal morbidity and mortality. The pathologic correlates of congenital bacterial infection include acute chorioamnionitis, acute villitis, and acute intervillositis. The strength of the association of congenital bacterial infection differs among these pathologies. Acute chorioamnionitis results usually from an ascending infection, and damage to the fetus is thought to be cytokine driven rather than damage secondary to bacteremia. Acute villitis is strongly associated with fetal sepsis due to congenital infections. A much less common variant on acute villitis pattern has been described with additional presence of bacteria in the fetal capillaries of the chorionic villi. We describe the spectrum of bacteria that would induce this unique pattern. The histological archives were searched from 2 institutions for cases with intravascular bacteria present in the villous capillaries of the placenta. Thirteen cases were identified, of which 11 cases had acute chorioamnionitis and all cases showed an acute villitis. Eight cases had Escherichia coli identified and 3 cases had Group B Streptococcus. All cases were associated with fetal death. In 9 cases, the mother showed signs of a significant infection including 1 maternal death. We conclude that finding intravascular bacteria is a serious complication of congenital infection with serious fetal and maternal sequela.