title: Embryonic staging using a 3D virtual reality system.
abstract: BACKGROUND
  The aim of this study was to demonstrate that Carnegie Stages could be assigned to embryos visualized with a 3D virtual reality system.
  
  
  METHODS
  We analysed 48 3D ultrasound scans of 19 IVF/ICSI pregnancies at 7-10 weeks' gestation. These datasets were visualized as 3D 'holograms' in the BARCO I-Space virtual reality system. Embryos were staged according to external morphological features (i.e. mainly limb development). After staging, the crown rump length (CRL) was measured. Stage and CRL were compared with gestational age based on the date of oocyte retrieval and with the classical data on embryology from the Carnegie Collection.
  
  
  RESULTS
  Embryonic staging was relatively easy because the I-Space allows depth perception, which helps in the estimation of size and position. The presumed stages corresponded well with the measured CRL. However, in 28 out of 48 cases, the stages seemed to have been reached earlier than previously described for the Carnegie Collection.
  
  
  CONCLUSIONS
  The I-Space, tentatively named Virtual Embryoscopy, is a promising non-invasive tool for early pregnancy evaluation. Combining embryonic growth with embryonic development opens a new area to study the relationship between embryonic growth, development and morphology, as well as second and third trimester pregnancy complications.
authors.affiliation: Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, PO Box 2040, Erasmus MC, University Medical Centre Rotterdam, 3000 CA Rotterdam, The Netherlands. c.verwoerd@erasmusmc.nl
authors.forename: C M
authors.initials: CM
authors.lastname: Verwoerd-Dikkeboom
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: N
authors.initials: N
authors.lastname: Exalto
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
mesh_terms: D018568:Crown-Rump Length; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014584:User-Computer Interface