The yolk sac is seen in early pregnancy through ultrasound and the absence of the obvious germ is caused by the following reasons: 1. the time of pregnancy is still relatively short, the embryo has not yet developed to the extent that the germ can be seen, it is recommended to project again according to the time of the last menstruation. 2. the vast majority of people can see the obvious germ tissue through ultrasound at about 6 weeks of menopause, but due to individual differences, some people may see it a little later, and it is also recommended to check the blood HCG and progesterone through blood sampling to see if the current development of the embryo is still normal. It is also recommended to check the blood HCG and progesterone through blood sampling to know whether the current embryo development is still normal or not, and to check it once every other day to understand the current embryo development through comparison and dynamic observation.