Can Ultrasound Analysis of the Yolk Sac be a Predictor of Pregnancy Outcome?

The Yolk sac is the first source of transfer between the mother and the embryo, with a nutritional and gas exchange function, vital for the development of the embryo, to which we can add primitive hematopoiesis, the production of stem cells and germ cells. Although normal-term pregnancies with abnormal aspects of the yolk sac have been described, the smaller or larger size of the yolk sac is associated with pregnancy loss. Our study aimed to determine whether the yolk sac size change, determined by measuring diameter (2D ultrasonography) or volume (3D ultrasonography), is independently associated with adverse pregnancy outcomes. The results of the study did not show a statistical significance between 2D and 3D measurements with adverse pregnancy outcomes, noting only an abrupt increase in the diameter and volume of the yolk sac preceding pregnancy loss. However, the evaluation of the yolk sac remains an important element in the ultrasound evaluation of pregnancy in the first trimester.