Recent advances in prenatal diagnosis and therapy has been made possible with the invention of newer imaging modalities

56 Introduction Recent advances in prenatal diagnosis and therapy has been made possible with the invention of newer imaging modalities including 3D and 4D ultrasound. Two dimensional ultrasound remains the method by which most fetal structural abnormalities are screened and diagnosed, however 3D and 4D are being used increasingly for the examination of the human fetus. Two dimensional scanning allows visualisation of static images while 3D and 4D imaging adds a further dimension to fetal study by allowing interaction with volume data sets to examine anatomic structures of interest in planes of section. This article will focus on the role of 2D, 3D and 4D ultrasonography in the diagnosis of fetal malformations and their value as a primary or adjunct diagnostic tool.