Metopic suture in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation.

Abstract

To investigate the development of the frontal bones and metopic suture in fetuses with trisomy 21 at 11 + 0 to 13 + 6 weeks of gestation. Three-dimensional (3D) ultrasound was used to measure the height of and gap between the frontal bones in 75 fetuses with trisomy 21 and these were compared to the measurements in 200 normal fetuses at 11 + 0 to 13 + 6 (median, 12 + 6) weeks of gestation. In the fetuses with trisomy 21, compared to the normal fetuses, there was no significant difference in either the height of the frontal bones (mean difference 0.16 SD, range -1.78 to 2.17 SD; P = 0.369) or the gap between them (mean difference 0.012, 95% CI -0.073 to 0.097; P = 0.780). Additionally, within the group of trisomy 21 fetuses there were no significant differences in the development of the frontal bones and metopic suture between those with absent (n = 46) and those with present (n = 29) nasal bone. In trisomy 21 the development of the frontal bones and metopic suture is as normal and is independent from the development of the nasal bones.