Vaginal bleeding after sex means bleeding during sex or just after having sexual intercourse, when you're not menstruating or don't expect to be menstruating. Vaginal bleeding after sex most commonly develops in women between the ages of 20 and 40.

Your cervix — the narrow, lower end of your uterus — is usually the source of vaginal bleeding brought on by sex, especially before menopause. Even if you have a healthy cervix, enough friction during sexual intercourse can cause bleeding. Inflammation of the cervix or some other abnormality can also result in bleeding.

In most cases, vaginal bleeding after sex is the result of harmless cervical changes, many of which don't require treatment.

If you're premenopausal and you have infrequent episodes of vaginal bleeding after sex — and you've had normal results on routine Pap tests — you don't need to see your doctor to be evaluated. If the vaginal bleeding bothers or worries you, you could make an appointment with your doctor to get it checked out.

If you're postmenopausal, vaginal bleeding at any time must be evaluated. Having atrophic vaginitis or other symptoms of vaginal dryness may be the reason that you're experiencing vaginal bleeding after sex. Your best bet is to consult with your doctor to be sure that the cause of vaginal bleeding isn't something serious.

Oct. 18, 2011