Evaluation of the utero-placental circulation by three-dimensional Doppler ultrasound in the second trimester of normal pregnancy.

Objective: To define normative data with three-dimensional (3D) Doppler ultrasound in the second trimester spiral arteries and placental volume blood flow.

Methods: An entry criterion was a documented singleton pregnancy at 14-25 weeks with normal outcome. Each patient had a 3D power Doppler exam. Automatic volume acquisition of the placental and spiral arteries blood flow was obtained. We calculated vascularization index (VI), flow index (FI) and vascularization flow index (VFI). The patients were further divided into subgroups based on two gestational week intervals. The outcome measure was normal pregnancy outcome.

Results: One hundred ninety-nine patients were included in this study. Placental and spiral arteries vascular indices slowly increased indicating progressive development of vascular network and increase in the volume blood flow. The range for placental VI was 11.43-14.63, FI was 37.44-40 and VFI was 4.77-6.06. The range for spiral arteries VI was 19-20.91, FI was 39.66-41.1 and VFI was 8.49-8.92. The mean gestational age at delivery was 38.18 weeks.

Conclusion: We defined normal 3D power Doppler vascular indices in pregnancies between 14 and 25 weeks of singleton gestation. The study indicated that placental and spiral arteries volume blood flow increased with the advancement of gestational age.