Heavy bleeding in the early stages of pregnancy with no detectable gestational sac may be caused by miscarriage or ectopic pregnancy. You should go to the hospital as soon as possible for a blood test to clarify the level of HCG, human chorionic gonadotropin, in the blood, and promptly determine whether it is a possible miscarriage or ectopic pregnancy. 1. Miscarriage: a large number of early pregnancy can not be found in the gestational sac, this situation may be an early miscarriage, the chorionic villi and the separation of the meconium, the opening of the blood sinuses, and then began to bleed, the pregnancy may have been partially or completely out of the uterine cavity, so ultrasound can not be seen in the gestational sac, the situation should be timely to the hospital, the doctor will be targeted treatment, such as removal of the uterus. 2. Ectopic pregnancy: early pregnancy heavy bleeding can not detect the gestational sac, and the serum HCG value is significantly lower than the HCG value of intrauterine pregnancy, vaginal ultrasound can not see the gestational sac, but can be seen in the abdominal cavity bleeding, but also at the same time accompanied by vaginal bleeding, it may be an ectopic pregnancy, you should be as soon as possible to do surgery. If you can’t find the gestational sac in the early stage of pregnancy, it is recommended that you cooperate with a professional obstetrician and gynecologist as soon as possible to improve the relevant examinations, to clarify the cause and early treatment.