If a woman bleeds during sex, there are several possibilities: 1. cervical lesions. 2. vaginal inflammation. 3. it is possible that sexual intercourse stimulates uterine contraction, causing the endometrium to shed and causing bleeding. In order to make a clear diagnosis, it is recommended to visit the gynecology department of the hospital. First, a gynecological examination should be done to find out whether there is any inflammation in the vulva and vagina, and whether there is any abnormal cervical redundancy, erosion, contact bleeding, etc. Ultrasound examination should also be done to find out whether there are any occupying lesions in the uterine cavity and the thickness of the endometrium. If the bleeding is considered to be caused by cervical lesions through the above examinations, cervical cytology, HPV testing, colposcopy and cervical biopsy if necessary are recommended for a definitive diagnosis.