After the appearance of the yolk sac, the fetal buds and the fetal heart can be seen under the ultrasound at the latest around 10~20 days. In normal pregnancy, when menopause is about 35 days, ultrasound can see a round or oval gestational sac in the uterine cavity, and then gradually appear the embryo buds, which usually appear on the 40th to 50th day of pregnancy. The fetal heart appears about 10 days after the appearance of the buds, that is, about 8 weeks of pregnancy; after seeing the yolk sac appears about 20 days, you will see the fetal buds and the fetal heart. If the yolk sac appears more than 20 days without seeing the fetal heart and fetal buds, it is likely to be a miscarriage, you need to consult a doctor in a timely manner, follow the doctor’s instructions to carry out reasonable treatment, to avoid the occurrence of a retained miscarriage, hemorrhage and other serious situations, pregnant women should pay attention to the rest of the daily routine to avoid fatigue, pay attention to nutrition. If the yolk sac does not see the fetal heart buds, you need to consult a doctor in a timely manner to avoid delaying the condition and bringing serious consequences, if you feel unwell, you should go to the hospital in a timely manner, consult a doctor for guidance.