Myelopoiesis in the liver of stillborns with evidence of intrauterine infection.

CONTEXT: Chorioamnionitis is the maternal and fetal response to an ascending intrauterine infection. The fetal response is manifested by funisitis and chorionic vasculitis, or as neutrophils within pulmonary spaces. Human hematopoiesis occurs in the liver primarily during the 6th to 22nd weeks of gestation.
OBJECTIVE: To establish the relationship between the presence of an intrauterine infection and the degree of fetal hepatic myelopoiesis in second- and third-trimester fetuses.
DESIGN: Liver and lungs from 49 fetal autopsies, 20 to 41 weeks of gestational age, and their associated placentas and membranes were analyzed for evidence of intrauterine infection and hepatic myelopoiesis. Hematoxylin-eosin-stained sections from fixed tissues were evaluated for the presence of amnionic fluid infection, defined by the presence of acute chorioamnionitis or funisitis. The degree of portal hematopoiesis, myelopoiesis and intra-alveolar neutrophils was assessed semiquantitatively with hematoxylin-eosin-stained sections and immunohistochemically with antimyeloperoxidase. The Kruskal-Wallis 1-way analysis of variance and the Wilcoxon-Mann-Whitney test were used to determine the significance of any observed difference.
RESULTS: The degree of portal and lobular myelopoiesis was significantly greater with the presence of inflammation in both the membranes and umbilical cord, and correlated with the presence of intra-alveolar neutrophils (P < .001). A high correlation between the hematoxylin-eosin and immunohistochemistry assessment of myeloid cells was noted.
CONCLUSIONS: There is increased portal and lobular myelopoiesis in 20-week to 41-week gestational age fetal livers that is associated with intrauterine ascending infection. The presence of increased portal or lobular myelopoiesis suggests the presence of an active fetal response to an intrauterine ascending infection.