Objective: To value the rate of chromosomal abnormalities and evolution of children who had a prenatal diagnosis of fetal nuchal translucency in the first trimester.
Material and methods: Multicenter prospective study conducted in 4,582 patients who had a first ultrasonography between 10 and 14 weeks' gestation (abdominal and/or transvaginal sonography). The measurement of fetal nuchal translucency was performed by mid-sagittal section and when it was higher than 2.5 mm a fetal karyotype was made.
Results: Three hundred and fifty eight nuchal translucencies (> 2.5 mm) were diagnosed and 334 karyotypes were done. We found 25 chromosomal anomalies (7.4%): 14 trisomies 21; 7 trisomies 18; 2 trisomies 13; one triploidy and one trisomy X. The postnatal examination of children detected three congenital malformations (0.9%): one facial dysmorphia, one complex abnormal heart anatomy and one renal agenesia.
Conclusion: Nuchal translucency (> 2.5 mm) is therefore a sonography sign associated with 7.4% of chromosomal anomalies. The distribution by size and mother ages is low. It should need superior larger-scale studies are needed for representative data. But this study shows that if fetal karyotype is normal, the incidence of congenital malformations seems to be the same by comparison with the general population.