Not seeing the yolk sac on 63 days examination may be a misdiagnosis, or it may be an empty gestational sac, or fetal arrest. Generally, the yolk sac can be seen through ultrasound examination around 42 days after menopause, and the absence of yolk sac in 63-day examination may be a misdiagnosis, which is a kind of result of the error of ultrasound examination, so you can change to other hospitals to go to check and judge again. The absence of a yolk sac at 63 days may also be an empty sac, which is caused by poor embryo quality and chromosomal abnormalities of the embryo, which is an abnormal pregnancy and cannot continue to be conceived. The absence of a yolk sac in the uterine cavity by ultrasound at 63 days may also be an ectopic pregnancy, in which the gestational sac may have been deposited in the fallopian tube, abdominal cavity, or ovary, which is an abnormal pregnancy that cannot be continued. The pregnancy can only continue if there is a yolk sac, buds, and a fetal heartbeat in the uterus.