The fetal frontomaxillary facial angle in normal and trisomy 21 ultrasounds at 11-13(+6) weeks of gestation: findings among the ethnic Chinese compared with Caucasian

Hsiao CH, Liu WL, Chen RC, Cheng BJ, Tseng YJ, Chu WC.

Prenat Diagn. 2013 Aug;33(8):711-5.


OBJECTIVE: The aim of this research was to compare the fetal frontomaxillary facial (FMF) angle between normal and trisomy 21 fetuses at 11(+0) -13(+6) weeks gestation in a Chinese population.

METHODS: A prospective observational study was performed that included 640 euploid and 45 trisomy 21 singleton pregnancies undergoing first trimester ultrasound screening between 11 and 13(+6) weeks of gestation. The FMF angle was measured in the midsagittal plane using the standard technique.

RESULTS: The fetal mean FMF angle decreased with the increasing crown-rump length (CRL) from 88.6°at a CRL of 45 mm to 78.5° at a CRL of 84 mm (FMF angle = 100.212 - 0.258 × CRL, R(2) = 0.222, p < 0.001). The overall mean FMF angle in the euploid population was 82.9° ± 4.1° and in trisomy 21 cases, 92.3° ± 5.2°.

CONCLUSIONS: Fetal FMF angle is affected by gestational age in a Chinese population, although it remains a significant predictor of fetal trisomy 21.


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