OC04.04: Post-hoc analysis of fetal anatomy and ultrasound markers in 3D-volumes acquired at 11–13 weeks gestation

To determine the ability to assess the fetal anatomy and ultrasound screening markers using 3D-volumes acquired during the 11–13 week scan. Women presenting for first trimester scanning were asked to participate in the study. When the routine ultrasound examination was completed, a single 3D-volume of the entire fetus was acquired (Philips IU22. Philips Ultrasound, Bothell, WA), using when possible a supine sagittal view as starting section. Post-hoc analysis of the volumes was performed by a single observer (AB), to identify three aneuploidy markers (nuchal translucency, nasal bone, and the frontomaxillary facial angle) in the sagittal view, and the following fetal structures navigating in the 3 orthogonal planes: sagittal, cross-sectional and coronal. From January to May 2008, 199 fetal volumes were acquired in singleton pregnancies at a mean gestational age of 12 + 2 weeks (range 11 + 2 − 13 + 3 weeks). The desired starting section was noted in 70% of the volumes. Satisfactory images for analysis were as follows, in the complete series and in the volumes acquired with the desired starting section: NT (83% and 93%), frontomaxillary facial angle (82% and 94%), nasal bone (65% and 78%), cranium and choroid plexus (88% and 95%), cord insertion (88% and 93%), diaphragm and stomach (86% and 98%), upper limbs (84% and 90%), bladder (66% and 69%), lower limbs (64% and 75%), spine and kidneys (39% and 47%), four chambers view (12% and 18%), face (4% and 3%), outflow tracts (0% and 0%). Post-hoc analysis of fetal ultrasound markers (NT, nasal bone and the facial angle) at 11–13 weeks, even when the supine sagittal view was used as starting section for volume acquisition, was feasible up to 94% of fetuses. Regarding fetal anatomy, correct visualization for head shape, stomach, diaphragm, umbilical cord insertion and upper limbs was achieved in about 90% of 3D-volumes.