Six weeks pregnant with a yolk sac, no fetal heart buds may be a normal situation, need to be combined with the menstrual situation to determine. 1. Women with regular menstrual cycles of 28-30 days can theoretically see the echoes of the pregnancy sac in the uterine cavity by ultrasound after 35 days of menopause, and the fetal heartbeat and buds can be seen after 6 weeks of menopause, and at the latest after 8 weeks of menopause, the fetal heartbeat and buds need to be seen. 2. If a woman’s menstrual cycle is irregular, especially if her menstrual cycle lasts 40 days or even a long time, how long it will take to see the fetal heart buds is uncertain, and it can be combined with the blood HCG to assess the gestational age. If the first ultrasound does not show the fetal heart buds, it is recommended to wait for the ultrasound to be rechecked for 1-2 weeks, and if it can see the fetal heart buds, it will generally not be a big problem. 3. If no fetal heartbeat can be seen on repeated ultrasounds at intervals of 1 week or so, it is necessary to consider the possibility of fetal arrest, and it is recommended that the pregnancy be terminated in a timely manner. Women should have regular checkups during pregnancy and seek prompt medical attention if they feel unwell.