HCG can be detected in the woman’s blood on day 2, so it can be detected in the woman’s blood as early as 7 days after intercourse. This test requires a blood test at the hospital, but if the patient does not have such a condition, she can test her own urine. Since the concentration of HCG in urine is relatively low, it can be detected only half a month after intercourse. If you want to test yourself, it is best to take a urine test half a month after intercourse.