The study of morphology and circulation of early embryo by three-dimensional ultrasound and power Doppler.

Three-dimensional (3-D) ultrasound plays an important role in obstetrics predominantly for assessing fetal anatomy. Presenting volume data in a standard anatomic orientation assists both ultrasonographers and pregnant patients to recognize anatomy more readily. Three-dimensional ultrasound is advantageous for the study of normal embryonic and/or fetal development, as well as providing information for families at risk for specific congenital anomalies by confirming normality. This method offers advantages in assessing the embryo in the first trimester as it is able to obtain multiplanar images through endovaginal volume acquisition. Rotation of the embryo and close scrutiny of the volume allow the systematic review of anatomic structures such as cord insertion, limb buds, cerebral cavities, stomach and bladder. Using this modality one can easily obtain the volumes of the gestational sac and yolk sac and can evaluate their relationship to prediction of pregnancy outcome. Three-dimensional power Doppler sonography has the potential to study process of placentation and evaluate the development of the embryonic and fetal cardiovascular systems. Three-dimensional ultrasound imaging in vivo compliments pathologic and histologic evaluation of the developing embryo, giving rise to a new term: 3-D sonoembryology. Rapid technological development will allow real-time 3-D ultrasound to provide improved and expanded patient care on the one side, and increased knowledge of developmental anatomy on the another.