[3-dimensional (3D) echography in obstetrics. Advantages and limits].

Three-dimensional ultrasound (3D) offers new options in imaging modes: such as simultaneous rotation and translation of the three perpendicular planes displayed, surface rendering, or transparent mode providing an imaging of structures with high echogenicity (bones, skull). This new imaging mode is extending the field of conventional two-dimensional ultrasound, but for now it has to be evaluated.