Acute atherosis in pregnancies complicated by hypertension, small-for-gestational-age infants, and diabetes mellitus.

A clinicohistologic study of acute atherosis in late complicated pregnancy was undertaken. Maternal vessels in the placental basal plate, underlying the amniochorial membranes and in placental bed biopsy specimens, were examined histologically. The earliest histologically convincing lesion acceptable as acute atherosis was fibrinoid necrosis with a perivascular mononuclear cell infiltrate, while lipophages were a late phenomenon. Any maternal uterine vessel that had not undergone physiologic vascular changes could be affected by acute atherosis. Acute atherosis was not seen in normal pregnancies or in pregnancies of diabetic women but was seen in pregnancies complicated by preeclampsia, small-for-gestational-age infants, or both. In pregnancies complicated by small-for-gestational-age infants, acute atherosis was not seen in the vessels in the decidua parietalis.