3-DIMENSIONAL ULTRASONOGRAPHIC ASSESSMENTS OF FETAL DEVELOPMENT

Objective: To visualize fetal surface anatomic structures in advancing gestation by use of three-dimensional ultrasonography with a speciall y developed abdominal three-dimensional transducer. Methods: One hundr ed six normal fetuses from 9 to 40 weeks' gestation were studied with a specially developed abdominal three-dimensional transducer (3.5 MHz) . This imaging system can provide conventional two-dimensional ultraso nography images and also can generate within seconds high-quality thre e-dimensional images in the surface and transparent modes with no need for an external workstation. We determined percentage of surface anat omic structures visualized at each trimester using two-dimensional and three-dimensional ultrasonography. Results: The number and the clarit y of surface anatomic structures increased from the first to the third trimester of pregnancy. The image quality was less distinct in the fi rst trimester because of the small fetal size. The ability to view the fetal face, hands, and feet was better with three-dimensional ultraso nography than with two-dimensional ultrasonography in the first trimes ter (P <.05), whereas fetal genitals were viewed better with two-dimen sional ultrasonography than with three-dimensional ultrasonography in the second and third trimesters (P <.05). Conclusion: Three-dimensiona l ultrasonography provides a new means of visualizing surface anatomic structures of the fetus in utero. Our results suggest that three-dime nsional ultrasonography has the potential to be a supplement to two-di mensional ultrasonography and should be useful in evaluating fetal abn ormalities in high-risk pregnancies. (C) 1998 by The American College of Obstetricians and Gynecologists.).