Reproducibility of the study of placental vascularization by three-dimensional power Doppler.

Aims: To assess the reproducibility of 3D power Doppler study of placental vascularization in order to establish its methodological bases for its further application in normal and pathological pregnancies.
Methods: A prospective study was carried on 30 normal singleton pregnancies from 14 to 40 weeks. To evaluate placental vascularization 3D power Doppler was applied to obtain a "placental biopsy". The spherical volume acquired was analyzed using the VOCAL imaging program. Two consecutive measurements were taken from each patient by a single observer, obtaining a total of 60 datasets. Placental volume (PV), Mean Gray (MG), Vascularization Index (VI), Flow Index (FI) and Vascularization Flow Index (VFI) were calculated. Intra-class correlation coefficient (ICC) and intra-observer agreement was evaluated.
Results: PV and MG presented an ICC of 0.98 and 0.94 respectively, with differences approaching zero. All 3D power Doppler vascular indices (VI, FI and VFI) showed a correlation greater than 0.85, with a better intra-observer agreement for the flow indices (FI and VFI).
Conclusions: Placental vascular biopsy through 3D power Doppler is a new and simple tool to routinely study placental vascularization in human pregnancy. Our results provide the validation of the technique demonstrating a good reproducibility of the 3D power Doppler parameters when applied to the study of the placental vascular tree in normal pregnancies.