First-trimester nuchal translucency: a risk analysis on fetal chromosome abnormality

PURPOSE: To investigate the importance of nuchal translucencies in the first trimester of pregnancy as an ultrasonographic marker for fetal chromosome abnormalities. MATERIALS AND METHODS: One hundred two first-trimester fetuses with a nuchal translucency of 3 mm or more were karyotyped. Multiple logistic regression analysis was performed to estimate the risk of fetal chromosomal abnormalities related to nuchal translucencies. RESULTS: Fifty-five (54%) of the fetuses had a normal karyotype. Forty-seven (46%) had an abnormal karyotype. The risk of chromosome abnormality was strongly increased in fetuses with a septated nuchal translucency compared with fetuses with a nonseptated nuchal translucency. CONCLUSION: First-trimester nuchal translucency is an important ultrasonographic marker for chromosomal abnormalities in the fetus. The presence of a normal karyotype in a fetus is a strong indication that detailed ultrasonographic examination for associated anomalies should be undertaken.