The size of the fluid dark area of the gestational sac is not strictly defined, generally need to comprehensive dynamic judgment, combined with blood HCG and embryonic development. In early pregnancy, due to the unstable development of the embryo, it is necessary to pay attention to appropriate rest, avoid strenuous exercise and exertion, ultrasound examination suggests that there is a small amount of fluid in the uterine cavity of the gestational sac, consider the possibility of preeclampsia, at this time need to be observed dynamically, if the blood HCG is normal, and the development of the embryo is normal, even if there is a liquid dark area will not be a big problem. If dynamic monitoring, the fluid dark area is stable or gradually shrinking, the embryo develops normally, generally not serious; while the fluid dark area increases progressively, the embryo develops sluggishly, or the HCG decreases, etc., which indicates that the embryo develops abnormally, which is relatively serious, and there is the possibility of miscarriage and fetal arrest. Early pregnancy must follow the doctor’s advice to carry out ultrasound examination to clarify the intrauterine pregnancy, and to understand the embryonic development. When the ultrasound suggests that there is fluid in the uterine cavity, it is also necessary to combine clinical symptoms and progesterone, blood HCG (human chorionic gonadotropin) level measurement and other tests, and if necessary, follow the doctor’s advice to actively preservation of the fetus treatment.