Bleeding after sex in girls is known as contact bleeding and is considered to be related to traumatic bleeding and pathologic bleeding. 1.Traumatic bleeding. (1) Women who have sex for the first time may have traumatic bleeding due to hymen tear, injury, etc., but the bleeding is small and can stop by itself. (2) Traumatic bleeding, which may also be caused by more severe vaginal destruction, will have pathogenic hemorrhage, usually occurs in the case of rough sexual intercourse, such as rape, resulting in vaginal mucosal tear, injury, and need to seek medical attention as soon as possible. 2. Pathological bleeding. (1) Inflammatory factors, such as the presence of vaginitis, cervicitis, endometritis and other diseases, will be due to inflammation invasion of the vaginal mucosa, then there will be contact bleeding after sexual intercourse. (2) Tumor factors, such as cervical cancer, cervical cancer and other diseases, may cause the vaginal mucosa to become brittle, which may cause contact bleeding after sex, and there may also be abnormal vaginal bleeding symptoms. (3) Other factors, such as cervical polyps, cervical erosion, cervical ectropion, etc., can also cause bleeding after sex. Women who bleed after sex should pay attention to the need to cooperate with the doctor as soon as possible to clarify the cause and give targeted treatment.