Usually, vaginal bleeding after sex is caused by several areas of bleeding, which should first be distinguished from the bleeding from the urethra to determine that it is vaginal bleeding. Depending on the location of the bleeding, it can be caused by a rupture of the vagina or vulva, or it can be caused by the cervix and the endometrium. Bleeding from the vulva, vagina and cervix is mainly due to inflammation or tumors, while bleeding from the endometrium should also be monitored for unwanted pregnancy. In particular, cervical bleeding is the most common symptom of cervical cancer and precancerous lesions, because vaginal bleeding after sex is the most common symptom. Therefore, it is recommended that patients with this symptom must go to the hospital promptly and usually undergo a combined cervical screening and pelvic ultrasound, which can find most of the causes of bleeding.