The yolk sac disappears and the HGC may or may not grow, depending on the gestational week of the pregnancy.
1. If you are just five weeks pregnant and only see the gestational sac on ultrasound but not the yolk sac, this is because the gestational week is still small and the yolk sac has not appeared yet, but the gestational sac is developing normally and the blood HCG will continue to grow and doubling is also normal.
2. If the pregnancy is already 6-8 weeks old, there is a yolk sac at the beginning but it disappears later, and the gestational sac is deformed and underdeveloped, it means that the development is not good, and it is very likely that the pregnancy will be aborted very soon, and the HCG will not continue to increase or even decrease in this case.
3. If the pregnancy has been more than 10 weeks, the yolk sac will disappear to form the other structures of the embryo, which belongs to the normal development process, the blood HCG to the 10th week of pregnancy to reach the highest peak growth, after 10 weeks will not only not grow but also will decline.
Before the 10th week of pregnancy, blood HCG and yolk sac, as well as progesterone are necessary to reflect the development of the gestational sac is good or bad, found that there is a problem should consult a doctor in time, if necessary, you can keep the baby.