The role of nuchal translucency in the screening for congenital heart defects

Assess the accuracy of the nuchal translucency (NT) measurement between 11 and 13 weeks and 6 days of gestation as a sonographic marker to screen for congenital heart defects (CHD).

This is a multi-center retrospective study in which singleton gestations of euploid fetuses were analyzed. NT measurement was performed in the first trimester examination when the fetal crown-rump length (CRL) was 45 to 84 mm, according to the criteria established by the Fetal Medicine Foundation. The cases were followed up to one month postpartum to assess the presence of CHD.

Three thousand six hundred and sixty four gestations were analyzed, of which twenty newborn infants had some congenital heart defect up to the first month of life (prevalence of 0.55%). The median NT in fetuses with CHD was 1.70 mm, and 1.60 mm in fetuses without CHD. However no statistically significant difference was observed between the two medians (Mann-Whitney test, p > 0.05). The NT sensitivity to detect CHD ranged from 15% to 20%, with a probability of false positive cases of 86.4% to 97.9%, depending on the cut-off point used. Odds ratio for CHD was high when compared to the classical indications for fetal echocardiography, ranging from 4.7 to 33.7, according to the cut-off point used.

Despite the low sensitivity of the test, increased NT is an important risk factor for CHD, and should be included in the strategy of prenatal screening for these diseases.