Evaluation of embryonic posture using four-dimensional ultrasound and virtual reality

Aim: To assess the possibility of embryonic posture evaluation (=feasibility, reproducibility, variation) at rest at 9 weeks' (+0–6 days) gestational age (GA) using four-dimensional ultrasound and virtual reality (VR) techniques. Moreover, it is hypothesized that embryonic posture shows variation at the same time point in an uneventful pregnancy. Methods: In this explorative prospective cohort study, 23 pregnant women were recruited from the Rotterdam periconceptional cohort. A transvaginal four-dimensional ultrasound examination of 30 min per pregnancy was performed between 9 and 10 weeks' GA. The acquired datasets were offline evaluated longitudinally (i.e. per frame) using VR techniques. Results: The ultrasound data of 16 (70%) out of 23 pregnancies were eligible for evaluation. At rest the analysis of the embryonic posture was feasible and showed a strong (>80%) intraobserver and interobserver reproducibility for most body parts. The majority of the body parts were in similar anatomic positions at rest. However, variations in anatomic positions (e.g. 6% rotated head, 9% laterally bent spine), within and between embryos, were seen at 9 weeks' GA. Conclusion: In this unique study, we showed for the first time that embryonic posture measurements at rest can be performed in a reliable way using state-of-the-art four-dimensional ultrasound and VR techniques. Already early in prenatal life there are differences regarding posture within and between embryos.