The presence of a yolk sac does not mean that there will soon be fetal buds. Under normal circumstances, after the fertilized egg is deposited on the uterine lining in the uterine cavity, the yolk sac will be produced in about 21 days, and about 1-2 weeks after the yolk sac is present, the fetal buds and the fetal heart will start to appear. However, the presence of a yolk sac does not mean that there will soon be fetal buds. For example, if there is an abnormality in the development of the embryo, resulting in fetal arrest, there may be no buds or fetal heart all the time, so you should pay attention to review the ultrasound in the hospital after one week. If there is still no fetal heart and buds after one week of ultrasound, after professional doctor’s diagnosis, it is clear that the fetus has stopped, you have to cooperate with the doctor as soon as possible to carry out clearance surgery. Therefore, the presence of yolk sacs does not necessarily mean that the fetus will develop healthily, but may also develop abnormally. If there are yolk sacs but no fetal buds and fetal heart, we should pay attention to it, and review it regularly to rule out the possibility of fetal arrest.