[Ultrasound echographic imaging and measurement of the amniotic cavity and yolk sac in early pregnancy: comparative study of intact and disordered pregnancies].

The chorionic cavity, vertex-breech length, yolk sac, and amnion were systematically demonstrated and measured in 50 early pregnancies, i.e., between the end of the sixth and the tenth week of gestation post menstruationem (p.m.). This was done in 23 cases with clinically and sonographically intact pregnancies without symptoms of abortion, in 12 cases with living embryos with symptoms of abortion, and in 15 cases of retained miscarriage. The thin amniotic membrane is sonographically demonstrated as a narrow, sharply defined reflected band in the chorionic cavity. In addition to direct demonstration of the amniotic membrane, the amniotic cavity can be demonstrated by a density difference in the echogenicity of the chorionic and amniotic fluids. While there are delicate, homogenously distributed inner echoes in the chorionic cavity, the amniotic cavity is empty save for the embryo structure. Sonographically, therefore, the amniotic cavity stands out as a spherical structure within the chorionic cavity. In all pregnancies with a living embryo it was possible to demonstrate the yolk sac sonographically as a sharply defined ring structure in the chorionic cavity. In 10 of the 15 cases of retained miscarriage only a rudimentary remnant of the yolk sac could be detected. The development of the amniotic and chorionic cavities and vertex-breech length was constant in the pregnancies with living embryos, the amnion developing synchronously with the vertex-breech length.(ABSTRACT TRUNCATED AT 250 WORDS)