ABSTRACT
Three-dimensional sonography has tremendously improved the quality of visualization of the fetus. The advantages of three-dimensional sonography have particularly improved the first-trimester scan. The limited manipulative capacity of the transvaginal probe has no impact on the quality of the scans. The acquired volumes containing data on embryonic morphology, can be rotated and transsected in an unlimited number of planes. Specific details of importance can be emphasized by different modalities of image-rendering. Hidden details of inner embryo structures can be depicted and clearly presented by the use of the ‘electronic scalpel’. Measurements have been improved to more accurate levels. The time of exposure of the embryo to the ultrasound energy is reduced to a minimum. Volume acquisition takes only a few seconds. Data are stored in a digital form and can be used for analysis at any time without any loss of quality and, in the same form, data are ready for telemedical application. Analysis of the developmental stages of the embryonic central nervous system is the most important issue of the first-trimester examination. In this review, we describe the state of the art of three-dimensional neurosonography in assessment of the normal anatomy and detection of anomalies during the first trimester of pregnancy.