Volume and vascularity of the yolk sac studied by three-dimensional ultrasound and color Doppler

The aim of our study was to assess the volume of the gestational sac and yo lk sac throughout the first trimester of pregnancy, and to establish the re lationship between the yolk sac volume measurements and vascularity visuali zation rates. Eighty women with uncomplicated singleton pregnancies between 5 and 12 week s were evaluated by three-dimensional and color Doppler ultrasound (Combiso n 530, Kretztechnik). Regression analysis revealed exponential rise of the gestational sac volume with gestational age throughout the first trimester. An exponential rise o f the yolk sec volume was noticed between gestational weeks 5 and 8, follow ed by gradual increase of the yolk sac volume between the gestational weeks 8 and 10. After reaching the plateau from 10 to 11 weeks, yolk sac volume started to decrease. The highest visualization rates for the yolk sac vesse ls were obtained between gestational weeks 7 and 8. When yolk sac reached t he maximum size between 10 and 11 weeks, reduced vascularity was demonstrat ed. Three-dimensional ultrasound allowed estimation of the gestational sac and yolk sac volumes throughout the first trimester of pregnancy. Both of these measurements seem to be useful prognostic parameters for the pregnancy out come. The combination of functional and volumetric data provides much usefu l information on early human development.