[Ultrasound studies in early pregnancy].

An ultrasound evaluation of the pregnancy in the first trimester is very helpful because no other method can better answer questions about the viability of the embryo, the true gestational age, the presence of an ectopic pregnancy and developmental anomalies at this early stage. Especially the introduction of vaginal sonography meant considerable progress in this area. Now there are normal growth curves available based on longitudinal measurements for the yolk sac, the amniotic and chorionic cavity and the crown-rump length. Significant deviations from these normal curves are suggestive of genetic anomalies of the developing child. Of these anomalies, detectable in the first trimester, especially the nuchal edema is associated with a high rate of chromosomal abnormalities. The fact that the gestational age can better be determined in the first trimester than in the later course of pregnancy is a strong argument for the introduction of routine ultrasound screening within the first twelve weeks of pregnancy.