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

Gestational sac volume and yolk sac volume and vascularity were measured in eighty women with uncomplicated pregnancy between 5 and 12 weeks of gestation. Regression analysis revealed an exponential growth of the gestational sac volume throughout the first trimester of pregnancy. Gestational sac volume measurements can be used for estimation of the gestational age in early pregnancy. Abnormal gestational sac volume measurement could be potentially used as a prognostic marker for pregnancy outcome. The yolk sac volume was found to increase from 5 to 10 weeks of gestation. However, when the yolk sac reaches its maximum volume at around 10 weeks it has already started to degenerate, which can be indirectly proved by a significant reduction in visualization rates of the yolk sac vascularity.