Distribution of nuchal translucency thickness at 11 to 14 weeks of gestation in a normal Turkish population

BACKGROUND/AIM: The aim of this study was to determine fetal nuchal translucency (NT) thickness nomogram values in first trimester in a Turkish population and compare them with previously reported European and Asian nomogram data. MATERIAL AND METHODS: Ultrasonographic measurements of crown-rump length (CRL) and NT thicknesses were obtained from 11 to 14 weeks of gestation in a normal Turkish population. Pregnant women with singleton pregnancy and fetal CRL between 45 and 84 mm were included in the study. The mean 1st, 3rd, 5th, 50th, 90th, 95th, 97th, and 99th percentiles and fixed cut off values of ≥ 2.5 mm, ≥ 3 mm, ≥ 3.5 mm NT thicknesses for a CRL between 45 and 84 mm were determined. RESULTS: A total of 1605 healthy fetuses were enrolled in the study. The sonographic measurements were performed on 1541 (%94) fetuses transabdominally and on 99 cases (%4) by the transvaginal route. The mean NT thickness for CRL between 45 and 84 mm was 1.57 ± 074 mm, and the mean 95th, 97th, and 99th percentiles of these values were 2.82 mm, 3.17, and 4.75 mm, respectively. The incidence of NT thicknesses at fixed points of ≥ 2.5 mm, ≥ 3 mm, and ≥ 3.5 mm in normal fetuses were 6.7%, 4.1%, and 2.1%, respectively. CONCLUSION: The present study demonstrated the nomogram data of fetal NT thickness in a Turkish population. We think that this report will be useful for further research related to NT thickness values on the prenatal diagnosis for the first trimester chromosomal abnormalities in Turkish populations.