The absence of a yolk sac at 6 weeks is generally normal, and you can observe the pregnancy for a period of time to determine whether it is an empty sac. No yolk sac at 6 weeks may be the result of a longer menstrual cycle, the fertilization of the egg is late, you can delay 1 week and then go to the hospital for review, 6 weeks of pregnancy can not see the gestational sac for the time being can be observed, do not have to draw conclusions too early. Delay 1 week to go to the hospital to do ultrasound, to determine that there is a gestational sac in the uterus for intrauterine pregnancy, and then check the buds, fetal heart to prove that the uterus is a live fetus, you can continue to carry on with the pregnancy, in the uterine cavity has not been able to see the gestational sac of the ectopic pregnancy, may be the bed in the fallopian tubes, the abdominal cavity, and so on, belongs to the abnormal pregnancy. Through the ultrasound can see the gestational sac, but there is no germ, fetal heart development belongs to the empty sac pregnancy, is also an abnormal phenomenon, can not be normal pregnancy. It is not necessary to check the time too early after pregnancy, so as not to see the gestational sac mood too anxious, affecting the normal development of the embryo.