It is recommended to test for pregnancy after 10 days of intercourse, and the most accurate way to test for pregnancy is to draw blood for HCG, which is known as human chorionic gonadotropin, and is secreted by the placenta on the seventh day after the formation of a fertilized egg. So the fastest way to detect an early pregnancy is on the eighth day after the formation of a fertilized egg. If a woman ovulates at the time of intercourse, HCG blood can be drawn on the eighth day after sex to detect pregnancy. If ovulation is delayed, HCG blood can be drawn at the latest about 10 days after sex to detect pregnancy. HCG test can only clarify whether a fertilized egg has formed, but whether the fertilized egg is lodged in the uterine cavity or outside the uterine cavity cannot be detected by drawing HCG blood. It is recommended to take a gynecological ultrasound examination after 10 days of menopause to determine whether the pregnancy is intrauterine or extrauterine.