[Ultrasonographic signs of chromosome aberrations]

We reviewed the literature on ultrasonographic criteria allowing prenatal diagnosis of chromosome aberrations, especially the most frequent: trisomy. Signs vary depending on the term of the ultrasound examination (first trimester ultrasound is often performed to early and several signs are observed in the second trimester). During the first trimester, the main criteria is the diagnosis of nuchal clearness 3 mm. The distance can only be measured with an appropriate sagittal CRL section by an experienced operator. The ideal term of this morphology ultrasound is 10 weeks gestation. During the second trimester, there are many suggestive criteria including non-specific signs: anomalous quantity of amniotic fluid, short femur, nuchal thickness 6 mm, isolated anomaly of the umbilical velocimetry, pyelectasy and fetal malformations (mainly cerebral or abdominal, including ophalocele and diaphragmatic hernia, anomalies, abnormal heart anatomy, cystic hygroma, facial anomalies and malformations of the members, often abnormal flexion of the hands).