Sonographic markers of aneuploidies at 6-10 weeks of gestation

Abstract

Objectives: To determine if sonographic features of live embryos at 6-10 weeks' gestation are altered in aneuploidies.

Methods: Embryonic crown rump length (CRL), embryonic heart rate, gestational sac diameter (GSD) and yolk sac diameter (YSD) were measured by transvaginal sonography in 5603 live embryos from singleton pregnancies at 6-10 weeks' gestation. The measurements were expressed as differences from the expected normal mean for CRL (delta values) and median delta values in the aneuploid cases were compared to the euploid group.

Results: 5393 pregnancies resulted in the live birth of phenotypically normal neonates and these cases constituted the euploid group. In 55 cases there was subsequent prenatal diagnosis of aneuploidies (trisomy 21, n=28; trisomy 18, n=10; trisomy 13, n=10; triploidy, n=4; Turner syndrome, n=3). The median and interquartile range (IQR) of delta embryonic heart rate in trisomy 18 was -19.44 (-23.77 to -7.20)bpm and in trisomy 13 it was 11.12 (7.25 to 20.39)bpm, which were significantly lower and higher, respectively, than in euploid embryos (median -0.05, IQR -6.18 to 6.21bpm). The median delta YSD in trisomy 21 was higher than in euploid fetuses (median 0.56, IQR 0.23 to 0.79 and median -0.17, IQR -3.11 to 2.82 mm). There were no other significant differences in measurements between the groups.

Conclusion: At 6-10 weeks' gestation there are sonographically detectable differences between euploid and trisomic embryos.