Placental blood flow measured by simultaneous multigate spectral Doppler imaging in pregnancies complicated by placental vascular abnormalities

Objective. To evaluate the role of placental blood flow measurements by simultaneous multigate spectral Doppler imaging in pregnancies complicated by intrauterine growth restriction (IUGR), and for early detection of placental vascular abnormalities in high- and low-risk pregnancies. Methods. To assess the sensitivity and specificity of abnormal placental blood flow in detecting IUGR, we followed 22 women whose pregnancies were complicated by IUGR at 28-34 weeks' gestation, and compared the findings with those obtained in 22 matched controls. We defined placental blood flow impedance as abnormal when 10% of placental pulsatility index (PI) measurements were greater than, or equal to, the mean umbilical artery PI (placental PI/umbilical PI ≥ 1). To determine the predictive value of abnormal placental blood flow measurement for identifying developing utero-placental insufficiency, we examined an unselected group of 100 low- and high-risk patients at 20-22 weeks' gestation. We correlated the Doppler findings with the development of pre-eclampsia, IUGR, placental abruption, oligohydramnios and the presence of persistent late decelerations during labor. Results. Placental blood flow determination was more sensitive than umbilical artery blood flow in detecting abnormal umbilical-placental flow impedances as manifested by the presence of IUGR. Of the 100 mixed high- and low-risk patients examined at 20-22 weeks, 32 had abnormal placental blood flow. Of these, 19 (59.4%) subsequently developed pathologies associated with placental vascular disease. Of the 68 patients with normal placental blood flow only six (8.8%) developed such pathologies. The sensitivity was 76% (19/25), with positive predictive value 59.4% (19/32); the specificity was 82.7% (62/75), with negative predictive value 91.2% (62/68). Conclusions. Abnormal intraplacental blood flow at 28-34 weeks' gestation is strongly associated with IUGR. In addition, it has moderate positive and negative predictive values for identifying subsequent development of uteroplacelatal vascular abnormalities.