ABSTRACT
Sonographic evaluation during the first trimester has become an effective screening method for structural and chromosomal abnormalities (1). 3DUS has been found to be an excellent tool that permits detailed and comprehensive evaluation of the embryo. One of the advantages of 3DUS compared to 2DUS is that the volume data acquired with the transvaginal transducer may be rotated to identify the desired structures irrespective of the plane of acquisition. In the first trimester, fetal head, face, neck, anterior abdominal wall, stomach, and spine can be examined routinely. This is particularly important in cases at risk for chromosomal abnormalities. Hull et al. showed that more anatomic structures were identified with 3DUS than 2DUS (Figs. 1 and 2), and that the length of time needed to obtain the desired structures was significantly less with 3DUS than with the conventional 2DUS (2.7 minutes vs. 14.7 minutes, respectively) (2). Michailidis et al.
