Vascularization of the placenta and the sub-placental myometrium: feasibility and reproducibility of a three-dimensional power Doppler ultrasound quantification technique. A pilot study.

OBJECTIVE: To assess the feasibility of placental and myometrial vascularization quantification using 3D power Doppler ultrasonography.

METHODS: 3D standardized acquisition was performed in the mid part of the utero-placental unit, once, in 38 patients undergoing normal pregnancies between 15 and 39 weeks. Vascularization parameters (VI, FI, and VFI) of placentae and myometrium were measured. Intra and inter-observer, as well as inter-acquisition reproducibility were evaluated.

RESULTS: Intra-class Correlation Coefficient of vascularization measurements were at least 0.94 for intra-observer, 0.92 for inter-observer, and 0.56 for inter-acquisition reproducibility. There was no significant difference for placental measurements for VI, FI and VFI between the second trimester and the third trimester pregnancies. Concerning the myometrium, we observed no significant difference between second and third trimester for FI. However, VI (28.090 vs. 19.374) and VFI (17.691 vs. 11.336) was significantly lower in the third trimester (p < 0.01).

CONCLUSION: 3D quantification of placental and myometrial vascular parameters is feasible with a high intra and inter-observer reproducibility. Evaluating a potential myometrial vascular impairment appears to be as relevant as studying the placenta alone and might be of great clinical interest. We believe that this technique should therefore be evaluated in clinical observational studies.