After 20 days of abortion, women bleed from the bottom after sex, which may be caused by premature coitus, or incomplete abortion, pelvic inflammatory disease or other factors. 1. Early coitus: generally at least one month after the abortion before coitus, so the abortion 20 days too early for sex, this time the uterus has not fully recovered, so in the process of coitus after the stimulation of vaginal bleeding. 2. Incomplete abortion: refers to part of the pregnancy out of the uterine cavity, and part of the residual in the uterine cavity or embedded in the cervix, and then affect the uterus contraction, the appearance of abortion after 20 days of sex, women’s bleeding below the situation. 3. Pelvic inflammatory disease: this disease is mainly caused by pathogenic microbial infections, such as Neisseria gonorrhoeae, Chlamydia trachomatis, anaerobic bacteria, etc., can be spread through the mucous membranes of the reproductive tract upward, the blood circulation, the lymphatic system, etc., and can be triggered by sexual activity, infection after uterine cavity operation, poor hygiene and other factors, resulting in bleeding after sex after 20 days of abortion. In addition to this, endometritis, cervical polyps, cervicitis and other diseases should be considered. It is recommended that women who bleed after sex after 20 days of miscarriage should go to the hospital in time to clarify the specific cause and follow the doctor’s instructions for treatment.