If vaginal bleeding occurs on the last day of menstruation, if it is dark red blood, it is probably due to the fact that the menstrual blood remains in the uterine cavity and is not completely cleared, and after intercourse, the residual menstrual blood is discharged outside the vagina by external force. In this case, since the menstruation is not yet completely clean and the endometrium is not yet completely repaired, intercourse is likely to cause pathogenic infection. If the bleeding is fresh, it is likely to be caused by local lesions of the cervix. It is recommended to have a gynecological examination to understand the specific location of the bleeding and to know whether there is chronic inflammation of the cervix and whether there are cervical polyps, and it is also recommended to have a screening for cervical cancer.