Transvaginal ultrasound in the first trimester of pregnancy

Abstract Recent improvements in transvaginal ultrasound permit the extremely detailed observation of the morphology of the early conceptus in utero. It is possible to use the term “sonoembryology” for the Aneation and observation of features such as brain vesicles and the neural tube as early as at the beginning of the 7th week of gestation. In this paper, sonoembryology from 4 to 11 weeks of gestation is briefly described.