Events from ovulation to implantation studied by three-dimensional ultrasound.

During the last decade transvaginal color Doppler has played an important role in increasing understanding of early human development. Although our knowledge of early pregnancy development has recently improved, little is known about the most critical period of human development: between conception and implantation. Recent advances in 3D ultrasound have made studies of follicular development, ovulation and uterine receptivity more accurate. The same method can be used for evaluation of the Fallopian tube patency and assessment of the ovarian and uterine causes of infertility which hamper processes of early human development. Storage capacities, reconstruction of the volume images and simultaneous viewing of all three orthogonal planes are the main advantages of this method. Introducing 3D ultrasound into assessment of early pregnancy has enabled visualization and volume estimation of the gestational sac, yolk sac and embryo. Switching on power Doppler superimposed to 3D gray scale can detect early vasculogenesis within the intervillous space and embryo/fetus. Here we review the potential application of this novel technique in monitoring the morphological and functional processes from ovulation towards implantation and early pregnancy.