[Three-dimensional sonoembryology--myth or reality]

To describe the normal development of the embryonic central nervous system (CNS) using three-dimensional (3D) transvaginal (TV) ultrasound (US) between 7 and 10 w.g. and to compare the embryonic development visualized by 3D TV US with that of the classical embryology.

A prospective longitudinal study was conducted over a period of 10 months with high-end ultrasound equipment (Voluson 730 Expert, GE Healthcare, U.S.). Thirty six pregnant women between 7 and 10 weeks of gestation (w.g.) were examined. In all cases a high-frequency 30 TV probe was used to acquire a 3D volume of the embryo, including the cranial pole. Subsequently, the acquired volume information was post-processed and analyzed with specialized software 4D View ver. 9.1 (GE Healthcare, U.S.). The duration of the examinations was about 15 minutes.

Three-dimensional TV US allows adequate visualization of the embryonic CNS in accordance with the Carnegie stages from the classical embryology. In 7 w.g. it is possible to identify the diencephalon (future third ventricle), mesencephalon (future aqueductus Sylvii), rhombencephalon (future fourth ventricle), and the two hemispheres. In 8 w.g. the choroid plexus in the lateral ventricles, the fourth ventricle and the cerebellum can also be recognized. The developmental changes in the size, shape and relationship of the described structures can be progressively assessed in 9 and 10 w.g.

Implementation of high-frequency 3D TV probes allows good visualization of the developing embryo, detailed anatomical description of all main cerebral structures, as well as adequate reconstruction of the brain ventricular system between 7 and 10 w.g. There is a good correlation between the embryonic development visualized by 3D TV U.S. and that of the classical embryology.