Study of Placental Vascularization Using Contrast Ultrasound

Preeclampsia and intrauterine growth restriction (IUGR) are two principal complications of pregnancy. These diseases are related to placental dysfunction nevertheless knowledge of its pathophysiological mechanisms remains inadequate.

No etiological treatment for these pathologies is available. Inducing birth is the only way to prevent the occurrence of these complications (such as fetal death in utero.

Therefore, a better understanding of placental vascularization under pathological and physiological conditions is necessary. This placental vascularization evolves throughout gestation. Histological studies have improved our knowledge of placental vascular pathologies; however, these are ex vivo data that only provide an incomplete reflection of placental function. In vivo placental studies are therefore essential to understand the mechanisms of placental perfusion. Currently, these studies are limited because the available tools (such as placental Doppler) do not allow for the separate study of maternal placental flow from fetal flow. However, histological evidence clearly establishes maternal placental vascular involvement in IUGR. It would therefore be interesting to study maternal and fetal placental vascularization separately. The development of new in vivo imaging exploration techniques will help to better understand placental pathologies.

In obstetrics, CES would offer the opportunity to study in vivo placental vascularization in a segmented manner (maternal versus fetal side independently) since the microbubbles do not cross the placental barrier. Animal studies show no toxic effects on fetal development nor any crossing of the placental barrier. In humans, the innovative use of this contrast agent has allowed for a better understanding of placental vascularization in the first trimester of pregnancy.