Three-dimensional ultrasonography in the first trimester of human pregnancy

Our purpose was to visualize normal embryonal and fetal surface anatomicalstructures in the first trimester of human pregnancy by use ofthree-dimensional ultrasonography with a specially developed abdominalthree-dimensional transducer. Four embryos and 31 fetuses of 8-13 weeksgestation were studied with a specially-developed abdominalthree-dimensional transducer (3.5 MHz). This imaging system can provideconventional two-dimensional ultrasonography images and can also generate,within seconds, high-quality three-dimensional images in the surface andtransparent mode with no need for an external workstation. The percentageof surface anatomical structures visualized at each gestational ageinterval using two-dimensional and three-dimensional ultrasonography ispresented. Head and trunk were depicted in all cases. The number and theclarity of visualization of face, upper and lower extremities, hand, andfoot increased with advancing gestation. The free loop of the umbilicalcord was depicted in most cases. The number of depictions of abdominal cordinsertion, midgut herniation, and yolk sac decreased with the increase ofgestation. Genitals could not be identified in the first trimester. Theability to view some surface anatomical structures (face, hand, and foot)was better with three-dimensional ultrasonography than with two-dimensionalultrasonography. Three-dimensional ultrasonography provides a novel meansfor visualization of surface anatomical structures of the embryo and earlyfetus. These results suggest that three-dimensional ultrasonography canbecome an important modality in future embryological and early fetalresearch and in detection of embryonic and fetal developmental disorders inthe first trimester of pregnancy.