The HCG value will gradually decrease after delivery, usually within 2 weeks after delivery, and will return to normal range around 1 month after delivery, with normal value of 0-5 IU/L. If the HCG value cannot return to normal range for a long time after delivery, it generally indicates that pathological conditions may exist, and the common reasons are as follows: 1. Intrauterine residue: If the HCG continues to be greater than normal value in 4 weeks after delivery, ultrasound examination is needed in time to determine whether there is placenta and fetal membrane residue. After diagnosis, different treatment methods need to be taken according to the area and size of the residue. If the intrauterine residue is small, we can promote uterine contraction and anti-infection treatment, and then review the ultrasound after 3-5 days. If the intrauterine residue is still not discharged or if the residue is large, we may need to carry out uterine clearance treatment; 2. Trophoblastic tumor: If the ultrasound examination shows that there is no placental residue, but the HCG still continues to be high after delivery, or rises again after decreasing, we need to consider the possibility of malignant trophoblastic tumor, such as staphyloma, malignant staphyloma, chorionic carcinoma, etc. malignant gravida, choriocarcinoma, etc. In this case, surgery and histopathological examination should be performed. If the examination results suggest erosive staphyloma or choriocarcinoma, the diagnosis can be made clearly and radiotherapy and surgery should be performed as soon as possible.