Bleeding during intercourse 20 days after the end of menstruation may be due to cervical cancer, endometritis, trichomonas vaginitis and other causes. Symptomatic treatment, such as medication, is usually taken, and surgery is performed when necessary. 1. Cervical cancer: High-risk HPV (human papillomavirus) infection is the main risk factor for cervical cancer. 90% of cervical cancers are associated with high-risk HPV infection. Early stage is mostly contact bleeding, middle and late stage is irregular vaginal bleeding. The amount of bleeding varies according to the size of the lesion and the invasion of blood vessels in the interstitium, and if it invades the large blood vessels, it can cause hemorrhage. Surgery is mainly used for early stage cervical cancer patients. Radiotherapy can also effectively treat cervical cancer. 2. Endometritis: such as menstruation, labor, abortion, weakening of the barrier effect of endometrium may cause bacterial invasion, resulting in endometritis. According to the duration of the disease, it can be divided into acute endometritis and chronic endometritis. Treatment is based on antibiotic therapy and, if necessary, surgery. Commonly used drugs for endometritis include: ceftriaxone, metronidazole, doxycycline and so on. 3. Trichomonas vaginitis: Trichomonas vaginitis is caused by Trichomonas vaginalis infection. The main way of transmission is through the direct transmission of sexual life. It can also be spread indirectly through baths, swimming pools, and other public supplies. It is usually treated with medication, such as metronidazole and tinidazole. There may also be other reasons for bleeding after menstruation, it is recommended to seek medical attention as soon as possible to rule out abnormalities, do not self-medication, to avoid delaying the condition, endangering the safety of life.