Reference Range of Embryo Volume by 3-D Sonography Using the XI VOCAL Method at 7 to 10 + 6 Weeks of Pregnancy

ABSTRACT

We sought to establish normative data for three-dimensional ultrasound (3DUS) first-trimester embryonic volume using the extended imaging virtual organ computer-aided analysis (XI VOCAL) technique. This cross-sectional study involved 64 normal pregnancies at 7 to 10 + 6 weeks' gestation. Embryonic volume was obtained on 3DUS using the XI VOCAL technique with manual outline of 10 sequential planes. The mean, median, standard deviation, and maximum and minimum values were obtained for each week calculated. Polynomial regression models adjusted by the determination coefficient (R ²) were created to assess the correlation between embryonic volume and gestational age (GA) and crown rump length (CRL). The intraclass correlation coefficient (ICC) was used to calculate inter- and intraobserver reproducibility. Mean embryonic volume went from 0.20 cm³ (range 0.10 to 0.89 cm³) to 5.12 cm³ (range 2.90 to 5.98 cm³). Embryonic volume was strongly correlated with GA (R ² = 0.84) and with CRL (R ² = 0.87). There was a good inter- and intraobserver reproducibility of embryonic volume with ICC = 0.999 and 0.995, respectively. Reference range for 3DUS first-trimester embryonic volume using the XI VOCAL technique were generated for pregnancies at 7 to 10 + 6 weeks, with high inter- and intraobserver reproducibility.

KEYWORDS

First trimester of pregnancy - embryo - volume measurement - three-dimensional ultrasonography - nomogram

REFERENCES

• 1 Riccabona M, Nelson T R, Pretorius D H. Three-dimensional ultrasound: accuracy of distance and volume measurements.  Ultrasound Obstet Gynecol. 1996;  7 429-434
• 2 Blaas H G, Eik-Nes S H, Berg S, Torp H. In-vivo three-dimensional ultrasound reconstructions of embryos and early fetuses.  Lancet. 1998;  352 1182-1186
• 3 Aviram R, Shpan D K, Markovitch O, Fishman A, Tepper R. Three-dimensional first trimester fetal volumetry: comparison with crown rump length.  Early Hum Dev. 2004;  80 1-5
• 4 Falcon O, Peralta C F, Cavoretto P, Faiola S, Nicolaides K H. Fetal trunk and head volume measured by three-dimensional ultrasound at 11 + 0 to 13 + 6 weeks of gestation in chromosomally normal pregnancies.  Ultrasound Obstet Gynecol. 2005;  26 263-266
• 5 Martins W P, Ferriani R A, Nastri C O, Filho F M. First trimester fetal volume and crown-rump length: comparison between singletons and twins conceived by in vitro fertilization.  Ultrasound Med Biol. 2008;  34 1360-1364
• 6 Guimarães Filho H A, da Costa L L, Araujo Júnior E, Pires C R, Nardozza L M, Mattar R. XI VOCAL (extended Imaging VOCAL): a new modality for three-dimensional sonographic volume measurement.  Arch Gynecol Obstet. 2007;  276 95-97
• 7 Cheong K B, Leung K Y, Chan H Y, Lee Y P, Yang F, Tang M H. Comparison of inter- and intraobserver agreement between three types of fetal volume measurement technique (XI VOCAL, VOCAL and multiplanar).  Ultrasound Obstet Gynecol. 2009;  33 287-294
• 8 Blaas H G, Taipale P, Torp H, Eik-Nes S H. Three-dimensional ultrasound volume calculations of human embryos and young fetuses: a study on the volumetry of compound structures and its reproducibility.  Ultrasound Obstet Gynecol. 2006;  27 640-646
• 9 Rolo L C, Nardozza L M, Araujo Júnior E, Nowak P M, Bortoletti Filho J, Moron A F. Measurement of embryo volume at 7-10 weeks' gestation by 3D-sonography.  J Obstet Gynaecol. 2009;  29 188-191