ABSTRACT
The recent development of ultrasound technology has resulted in remarkable progress in visualization of early embryos and fetuses and in the development of sonoembryology. With the use of three- and four-dimensional (3D and 4D) ultrasound, both structural and functional developments in the first 12 weeks of gestation can be assessed more objectively and reliably. New technology has moved embryology from postmortem studies to the in vivo environment. It is the purpose of this chapter to illustrate the potential of 3D/4D sonography in the study of the embryo and early fetus.
