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A Thai reference for normal fetal nasal bone length at 11-13(+6) weeks gestation
N Pruksanusak1, C Suwanrath, O Kor-anantakul
1Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkla University, Hat Yai, Thailand.
Aim:
The purpose of this study was to establish a Thai reference for normal fetal nasal bone length (NBL) at 11-13(+6) weeks gestation.
Methods:
The fetal nasal bone was measured by sonography in pregnant women at 11-13(+6) weeks gestation. All neonates who showed normal karyotypes were examined after delivery to confirm the absence of congenital abnormalities.
Results:
A total of 255 pregnant women were recruited. Forty-seven pregnant women were excluded from the analysis because of technically unsatisfactory examination or absent nasal bone and chromosomal abnormalities. The mean ± SD of NBL was 1.79 ± 0.33 mm and increased significantly with crown-rump length (CRL) and gestational age (p < 0.001). The best-fit equation for NBL in euploid fetuses in relation to CRL was: NBL (mm) = (0.030 × CRL (mm)) - 0.016.
Conclusion:
NBL in Thai fetuses at 11-13(+6) weeks was found to be on average shorter than that in Caucasian, African-American and Chinese populations, but similar to those reported in Korean and Latin-American populations.
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