The full name of HCG is chorionic gonadotropin, which is a glycoprotein hormone. The significance of having a chorionic gonadotropin test is mainly: first, to detect pregnancy, which is the most used in clinical practice. Chorionic gonadotropin in the blood rises significantly after pregnancy and doubles in early pregnancy as the duration of pregnancy increases. The doubling of chorionic gonadotropin is indicative of embryonic viability and needs to be monitored routinely during early pregnancy. Secondly, chorionic gonadotropin is meaningful for the diagnosis of gynecological diseases, such as gestational trophoblastic disease and chorionic carcinoma, where there is a slight increase in chorionic gonadotropin, but it does not double every other day as in pregnancy. Thirdly, patients with suspected placental implantation with retained placenta in the postpartum period need to monitor hormone levels, and if there is implantation or adhesions hormone levels will continue to remain unabated.