Diagnostic échographique des anomalies fœtales du premier trimestre de la grossesse (dépistage chromosomique par mesure de la clarté nucale exclue)

Complete anatomical survey of the foetus in the first trimester of pregnancy is possible, by transvaginal ultrasonography. Ideally, the ultrasonography should be performed between 12 and 14 weeks. At that time, a wide range of foetal congenital anomalies can be diagnosed, including defects of the central nervous system, heart, anterior abdominal wall, urinary tract, neck and skeleton. We studied 11,702 singleton pregnancies for which an ultrasonography was performed between 11 and 15 weeks at the Sonography and Foetal Medicine Unit of the CMCO in Schiltigheim/Strasbourg-France. We had a representative overview of the foetal abnormalities that could be observed in the first trimester, as most of these pregnancies were considered at high risk. 1313 abnormalities were suspected according to ultrasonographic examinations (11.2% of the studied population). Nuchal translucency, hygroma coli and Bonnevie-Ulrich syndrome were the most frequent abnormalities detected (more than 70%). Sensibility and specificity of the ultrasonographic investigations were evaluated. The first trimester ultrasonographic examination cannot detect all the malformations. However, it can detect the major ones and can define a high risk group that will need further assessment. It allows therefore early management. The anatomic ultrasonographic examination around 20 weeks gestation should also be performed, since a number of anomalies may not be evident at scanning during early pregnancy.