HCG <0.100mIU/ml means that the woman is not pregnant and does not have trophoblastic disease. The normal value of HCG when not pregnant is 0-10mIU/ml. if she is suffering from trophoblastic disease, the result of HCG <0.1mIU/ml after treatment means that the patient's HCG index has dropped to normal level.1. Pregnancy: HCG will be produced after the fertilized egg is laid, usually the blood HCG of women with intrauterine pregnancy is >10mIU/ml, and there is the phenomenon of doubling every other day, accompanied by menopause, The symptoms are accompanied by menopause, breast swelling, nausea, vomiting, etc. If the HCG is less than 0.100mIU/ml about 10 days after intercourse, it usually means that the woman is not pregnant. 2. Trophoblastic disease: including benign hyperplasia, erosive hyperplasia and choriocarcinoma. Usually, when trophoblastic disease is present, the blood HCG will be abnormally high and show symptoms such as pregnancy reaction and irregular vaginal bleeding. If HCG <0.100mIU/ml is found on retest, it means that after active treatment, serum HCG is stable and decreasing, and there is a possibility of cure.