Failure of physiologic transformation of the spiral arteries in patients with preterm labor and intact membranes

The purpose of this study was to determine whether abnormal placentation (defined as the failure of physiologic transformation of spiral arteries) is present in patients with preterm labor and intact membranes who delivered a preterm neonate. A cross-sectional study was conducted to examine the histopathologic findings in the placental bed and placenta of patients with preterm labor and intact membranes (n = 27), preeclampsia (n = 43), and healthy pregnant women at term (n = 103). Immunohistochemistry studies with cytokeratin 7 and periodic acid–Schiff were used to detect trophoblast and fibrinoid, respectively, and diagnose the failure of physiologic transformation of the spiral arteries. The mean percentage of spiral arteries with failure of physiologic transformation in the myometrium was significantly higher in patients with preterm labor and preeclampsia than in normal pregnant women at term ( P = .0004 and P