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

OBJECTIVE: 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). METHODS: Multicentric retrospective study, analyzing single pregnancies from euploid fetuses. NT measurement was performed in the first trimester, when fetuses had from 45 to 84 mm of crown-rump length (CRL), according to the criteria established by the Fetal Medicine Foundation. Cases were followed until 1 month after delivery to verify the presence of CHD. RESULTS: 3,664 pregnancies were analyzed and 20 newborns had CHD diagnosed until the first month of life (prevalence of 0.55%). The median NT of the fetuses with CHD was 1.70 mm and 1.60 mm for fetuses without CHD, however no significant difference was found (Mann-Whitney test, p > 0.05). The sensitivity of NT in detection of CHD varied from 15% to 20%, with a range of false positive probability from 86.4% to 97.9%, depending on the cut-off point used. However, the odds ratio was high, compared to the classic indications of echocardiography, ranging from 4.7 to 33.7 according to the cutt-off point. CONCLUSION: In spite of the low sensitivity of the test, enlarged NT is an important risk factor for CHD and should be used in prenatal screening for CHD.