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Normal ranges of embryonic length, embryonic heart rate, gestational sac diameter and yolk sac diameter at 6-10 weeks.
Papaioannou GI, Syngelaki A, Poon LC, Ross JA, Nicolaides KH.
Fetal Diagn Ther 2010;28:207-19. -
Gestational sac volume measured by three-dimensional ultrasound at 11 to 13 + 6 weeks of gestation: relation to chromosomal defects.
Falcon O, Wegrzyn P, Faro C, Peralta CF, Nicolaides KH.
Ultrasound Obstet Gynecol 2005;25:546-50.