The presence of a yolk sac does not necessarily mean that there will be a fetal bud or heartbeat; there is no direct link between the two. The presence of a yolk sac inside the uterine cavity indicates an intrauterine pregnancy and can exclude an ectopic pregnancy. However, the presence or absence of a fetal bud or heartbeat requires continued observation. In some women, the presence of fetal buds and fetal heartbeats is not yet observable due to their small size and it may take some time before they can be detected, and the presence of fetal buds and fetal heartbeats is affected by many factors. If the progesterone in the body is low or if there is a viral infection, the embryo may stop developing and no fetal bud or fetal heart will appear. If you are overworked, stressed, have an endocrine disorder, or have problems with the quality of your sperm or eggs, it may affect the growth and development of the embryo, and no germ or heartbeat will appear.