It is important to be evaluated by a doctor
if your bleeding during or after sex is persistent or a frequently recurrent issue. It may indicate a medical problem, but in most cases, if promptly diagnosed it is treatable. The source of bleeding commonly brought on by sexual intercourse is most likely the cervix, which is rich in blood vessels. It is normal to bleed when there is too much friction and not enough lubricant to reduce the friction. Bleeding can also occur if the cells of your cervix are inflamed or contain a lesion such as abnormal cells that any injury
to it could cause bleeding much more easily. Two common sexually transmitted disease that can cause vaginal bleeding after intercourse are chlamydia or gonorrhea if you also experience other symptoms such as vaginal discharge, irritation or a burning sensation when urinating. Vaginitis is the inflammation of the vagina that may also cause bleeding after intercourse. Pelvic inflammatory disease and endometriosis
may also lead to vaginal bleeding during or after intercourse. There are a number of other possible causes that I would recommend visiting an OB-GYN who can help you identify a cause. Your doctor needs to perform a thorough pelvic examination and may order diagnostic tests to look closely at your cervix for any abnormal cells like tumors or polyps on the cervix or vaginal wall and also a PAP smear to check for cervical cancer if you've not had one done recently.