There is no such thing as HGC, it should be HCG, which is an acronym for chorionic gonadotropin, a hormone secreted by the cells of the syncytial trophoblast after pregnancy, which protects the gestational sac from attacks by the maternal immune system. It can be detected in the blood 10 days after sexual intercourse and is clinically known as a positive blood chorionic gonadotropin, which is a sensitive indicator of early pregnancy. If your period is overdue for more than three days after sex, you can buy an early pregnancy test paper and use the morning urine to check for pregnancy.