title: First-trimester crown-rump length and embryonic volume of aneuploid fetuses measured in virtual reality.
abstract: OBJECTIVE
  To examine whether embryonic volume (EV), as measured using three-dimensional (3D) ultrasound and a virtual reality approach, is a better measure of growth restriction than is crown-rump length (CRL) in aneuploid fetuses.
  
  
  METHODS
  We retrospectively measured CRL and EV in prospectively collected 3D ultrasound volumes of 55 aneuploid fetuses using the Barco I-Space VR system. The gestational age ranged from 11 + 2 to 14 + 4 weeks. We compared our measured data with previously published reference curves for euploid fetuses. Delta-values were calculated by subtracting the expected mean for euploid fetuses of the same gestational age from observed values. The one-sample t-test was used to test the significance of differences observed.
  
  
  RESULTS
  The CRL measurements of fetuses with trisomy 21 (n = 26), trisomy 13 (n = 5) and monosomy X (n = 5) were comparable with those of euploid fetuses, but in fetuses with trisomy 18 (n = 19) the CRL was 14.5% smaller (P < 0.001). The EV in fetuses with trisomies 21, 18 and 13 and monosomy X was smaller than in euploid fetuses (-27.8%, P < 0.001; -39.4%, P < 0.001; -40.9%, P = 0.004; and -27.3%, P = 0.055, respectively).
  
  
  CONCLUSIONS
  When relying on CRL measurements alone, first-trimester growth restriction is especially manifest in trisomy 18. Using EV, growth restriction is also evident in trisomies 21 and 13 and monosomy X. EV seems to be a more effective measurement for the assessment of first-trimester growth restriction in aneuploid fetuses.
authors.affiliation: Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Centre Rotterdam, The Netherlands. l.baken@erasmusmc.nl
authors.forename: L
authors.initials: L
authors.lastname: Baken
authors.forename: P N A C M
authors.initials: PN
authors.lastname: van Heesch
authors.forename: H I J
authors.initials: HI
authors.lastname: Wildschut
authors.forename: A H J
authors.initials: AH
authors.lastname: Koning
authors.forename: P J
authors.initials: PJ
authors.lastname: van der Spek
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: N
authors.initials: N
authors.lastname: Exalto
mesh_terms: D000782:Aneuploidy; D018568:Crown-Rump Length; D005317:Fetal Growth Retardation / Q000473:pathology*; D005333:Fetus / Q000473:pathology*; D005865:Gestational Age; D006801:Humans; D021621:Imaging, Three-Dimensional; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods; D014584:User-Computer Interface