First of all, it can be confirmed that it is intrauterine pregnancy, and the fetal heart is faintly visible. This kind of intrauterine dark area found by B-ultrasound can be seen in many early pregnancy cases. Most of them are harmless. It is speculated that the fluid secreted by fallopian tube and uterine cavity will disappear automatically after embryo implantation, and a small amount of delayed absorption will disappear. Another situation is uterine bleeding. Either way, most of it will be absorbed without leaving any harm. Only darker and darker areas are danger signals. Therefore, it is still necessary to closely observe at present.