Placental Vascular Sonobiopsy Using Three-dimensional Power Doppler Ultrasound in Normal and Growth Restricted Fetuses

Abstract 

Objective

To investigate placental vascular sonobiopsy using three-dimensional (3D) power Doppler ultrasound to assess placental vascularization in normal and growth restricted fetuses.

Methods

Placental vascular sonobiopsy using 3D power Doppler ultrasound with the VOCAL imaging analysis program was performed on 208 normal fetuses between 12 and 40 weeks of gestation and 13 pregnancies with fetal growth restriction (FGR) at 22–39 weeks' gestation. Only pregnancies with an entirely visualized anterior placenta were included in the study. 3D power Doppler indices related to placental vascularization (vascularization index (VI), flow index (FI) and vascularization flow index (VFI)) were calculated in each placenta. Intra- and inter-class correlation coefficients and intra- and inter-observer agreements of measurements were assessed.

Results

A weak linear relationship was found between the gestational age and VI, FI, and VFI, respectively. VI values in 8 of 13 FGR pregnancies (61.5%), FI value in one FGR pregnancy (7.7%) and VFI values of 6 FGR pregnancies (46.2%) were below −1.5SD of the reference ranges for VI, FI and VFI, respectively. After 32 weeks of gestation, VI, FI, and VFI values in 10 FGR pregnancies were significantly lower compared to 79 normal pregnancies, respectively (P < 0.01). All 3D power Doppler indices (VI, FI and VFI) showed a correlation greater than 0.85, with good intra- and inter-observer agreements.

Conclusion

Our findings suggest that placental vascular sonobiopsy using 3D power Doppler ultrasound may provide new information on the assessment of placental vascularization in normal and FGR pregnancies, while placental perfusion is reduced in FGR compared to normal pregnancy. However, the data and its interpretation in our study should be taken with some degree of caution because of the small number of FGR subjects studied. Further studies involving a larger sample size of FGR pregnancies are needed to confirm the usefulness of placental vascular sonobiopsy using 3D power Doppler ultrasound in clinical practice.

Keywords: Placental vascular sonobiopsy, Three-dimensional power Doppler ultrasound, Placental vascularization, Normal fetus, Normal pregnancy, Fetal growth restriction