45 days to see the embryo.

If the menstrual cycle is regular at ordinary times, the fetal bud can be seen at about 42 days, and the original cardiovascular pulse can be seen at about 49 days. However, if the menstrual cycle is delayed or extra ovulation or delayed ovulation occurs, the time of showing the fetal bud will be delayed accordingly. Therefore, at 45 days of pregnancy, the fetal bud may be seen, but there may not be fetal heartbeat. If there is no pain in the lower abdomen and vaginal bleeding, repeat the ultrasound one week later to observe changes in the fetal heart and embryo bud. If the gestational sac is larger than 3 cm in diameter and still does not see the fetal heart and embryo bud, it is necessary to consider the possibility of embryo development.