Three-dimensional US is useful to identify the location and extent of facial clefting. The advantages of 3D US are the following: (a) The face may be viewed in a standard orientation, (b) the defect may be viewed systematically by using an interactive display, and (c) the rendered image provides landmarks for the planar images. Patient decisions may be affected, since they can view the abnormality on a recognizable 3D rendered image.

Thirty‐one high‐risk patients (16 to 35 weeks' gestation) underwent two‐dimensional and three‐dimensional ultrasonography to compare two‐dimensional and non‐cardiac‐gated three‐dimensional ultrasonography of the normal fetal heart. After normal two‐dimensional studies, three‐dimensional sonographic volumes were acquired without cardiac gating in transverse and longitudinal planes. Standard cardiac views were derived from three‐dimensional data, analyzed, and rated as follows: (1) not identifiable, (2) identifiable but inadequate for diagnosis, (3) adequate, and (4) excellent. Two‐dimensional ultrasonography demonstrated better yields of diagnostically acceptable images of basic echocardiographic views (four‐chamber view, 100% for two‐dimensional sonography versus 10 to 71% for three‐dimensional sonography; right ventricular outflow tract, 42% for two‐dimensional versus 6 to 26% for three‐dimensional ultrasonography; left ventricular outflow tract, 71% for two‐dimensional versus 13 to 45% for three‐dimensional sonography). In one subject three‐dimensional ultrasonography was superior to two‐dimensional sonography in demonstrating an outflow tract. Aortic and ductal arches were not imaged with the two‐dimensional technique but were available from the acquired three‐dimensional volumes in 3 to 32% and 23%, respectively. False‐positive and false‐negative findings were observed on three‐dimensional ultrasonograms. Overall, compared to two‐dimensional ultrasonography, non‐cardiac‐gated three‐dimensional sonography yielded inadequate reconstructed image quality of basic echocardiographic views (four‐chamber view, right ventricular outflow tract, left ventricular outflow tract). Three‐dimensional ultrasonography, however, shows potential for allowing nonechocardiographers to acquire some diagnostically acceptable views of the aortic and ductal arches.

The neural arch ossification centers in the distal fetal spine were evaluated with ultrasound (US) during the second trimester of pregnancy in 239 fetuses. Ossification of the neural arch centers occurred in a predictable pattern and in a caudal direction. An additional vertebral level became ossified every 2-3 weeks from L-5 through S-5 after 16 weeks gestational age; by 22 weeks, S-2 was ossified in all fetuses studied. Radiographic and histologic correlation was performed in one fetus, and the method of establishing vertebral level with US proved accurate. In addition, the origin of the echoes at US corresponded to the histologic ossification centers. In 95% of the fetuses, S-1 was at the top of the iliac wing. Therefore, the level of ossification in the distal fetal spine could be rapidly assessed. Ossification to S-2 by 22 weeks, with a normal transverse configuration, normal overlying integument, and normal cranial structures, should lead to reassurance in excluding neural tube defects, except for distal sacral lesions.

Three-dimensional ultrasound offers the potential to provide greater information in fetal hand evaluation for both normal and abnormal hands.