MATERNAL FLOOR INFARCTION - RELATIONSHIP TO X-CELLS, MAJOR BASIC-PROTEIN, AND ADVERSE PERINATAL OUTCOME

OBJECTIVE: Maternal floor infarction of the placenta is characterized by gross placental abnormalities and histologic evidence of X-cell proliferation. Previously, pregnancy-associated major basic protein has been localized to the placental X cell and identified at elevated levels in serum and amniotic fluid in all normal pregnancies. Here we test the hypothesis that pregnancy-associated major basic protein is localized to the X cells in maternal floor infarction and that it contributes to the pathophysiologic features of pregnancies complicated by maternal floor infarction. STUDY DESIGN: Seven patients with eight pregnancies complicated by maternal floor infarction were evaluated. We analyzed placental tissue, serum, amniotic fluid, and placental cyst fluid for pregnancy-associated major basic protein. RESULTS: Placental tissue from pregnancies complicated by maternal floor infarction had increased numbers of X cells and fibrinoid material that occupied or surrounded degenerating villi and that stained intensely for pregnancy-associated major basic protein. Serum pregnancy-associated major basic protein levels were variable and likely cannot be used to predict the occurrence of maternal floor infarction. CONCLUSION: Pregnancy-associated major basic protein, a potent cytotoxin, is localized to X cells and is deposited in close proximity to chorionic villi in maternal floor infarction and may contribute to the pathophysiology of this disorder.