YS pregnancy refers to the role of the yolk sac (YS) in early pregnancy. The yolk sac is a vital structure that provides nourishment and support to the developing embryo before the placenta is fully formed.
Here's a breakdown of the yolk sac's importance during early pregnancy:
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Early Nutrient Supply: Before the placenta takes over, the yolk sac is the primary source of nutrients for the embryo. It facilitates the exchange of substances between the mother and the developing baby.
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Formation and Visualization: The yolk sac typically appears around 5 weeks of gestation and can be visualized via ultrasound when the gestational sac diameter reaches 8-13 mm.
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Temporary Structure: The yolk sac is a temporary structure that eventually regresses as the placenta develops and takes over the role of providing nutrients and oxygen to the fetus.
In summary, the yolk sac is a critical structure in early pregnancy, providing essential support and nutrition to the embryo before the placenta is fully functional. Its presence and characteristics are important indicators of a healthy developing pregnancy during early ultrasound examinations.
