Sonoembryology by three-dimensional ultrasonography: pictorial essay.

CONTEXT: Three-dimensional ultrasonography in obstetrics has evolved in the last years, and nowadays it is a methodology that greatly helps prenatal diagnosis. Through its rendering mode it allows the careful evaluation of fetal face and limbs, and in multiplanar mode it allows the assessment of the anatomy through the many possible planes. In the first trimester of gestation, three-dimensional ultrasonography permits the detailed evaluation of embryonic development. Its main advantages over two-dimensional ultrasonography are shorter examination time and the possibility of storage of the volumes for later processing and analysis. AIM: We present a pictorial essay with normal embryo development in the first trimester of pregnancy by three-dimensional ultrasonography, from the fifth to ninth week.