3D Sonoembryology

Abstract

After the introduction of high-frequency transvaginal transducers in clinical obstetrics, the term 'sonoembryology' was first coined in 1990.1 Three-dimensional sonography performed with a transvaginal approach has expanded the depth of inquiry and allowed threedimensional sonoembryology. Transvaginal approach combined with high frequency (12 MHz) and a harmonic phase inversion method can provide us images with high quality and high resolution demonstrating detailed embryonal structures, including normal development of embryos and fetuses, and many congenital abnormalities, such as conjoined twin from 9 weeks, vertebral abnormality from 9 weeks, cleft lip/palate from 12 weeks, congenital cataract from 14 weeks, limb abnormality from 11 weeks, thoracoabdominal abnormality from 12 weeks of gestation. It is possible that by developing 3D neurosonoembryology imaging in utero, current fetal staging (which uses gestational age based on last menstrual period or crown-rump length measurement) may change into a 'morphological staging system', such as the Carnegie staging system, which has been central to embryology. A novel imaging technique of high-resolution transvaginal 3D sonography is illustrated in the definition of normal embryonic anatomy as well as in the identification of many congenital anomalies. They allow extending the detection of anatomical congenital anomalies to an earlier gestational age.