The slow growth of HCG and the absence of a gestational sac inside or outside the uterus may be caused by insufficient duration of pregnancy, biochemical pregnancy, etc. It is recommended to consult a doctor in time and follow the doctor’s instructions for treatment. 1. Insufficient pregnancy time: If the pregnancy time is too short, it can also lead to the slow growth of HCG, at this time, the gestational sac has not yet developed, therefore, you can not see the gestational sac, do not need to worry too much, it is recommended to wait for a week and then go to the hospital for review. 2. Biochemical pregnancy: under normal circumstances, after a woman is pregnant, HCG in the body will grow rapidly, if the HCG grows slowly, the gestational sac can not be seen inside and outside the uterus, may be due to biochemical pregnancy, the patient will appear vaginal bleeding, but also mistaken for menstruation, and may be accompanied by pain in the lower abdomen. Generally, no treatment is needed. If multiple biochemical pregnancies occur, the cause of the pregnancy should be actively searched for and targeted treatment should be made to facilitate a smooth pregnancy and delivery. In addition, the slow growth of HCG and the lack of visible gestational sacs inside and outside the uterus may be caused by other reasons, so it is recommended to consult a doctor in time and follow the doctor’s instructions to improve further examination.