Post-menopausal bleeding involves vaginal bleeding following a woman's last menstrual period. For the purposes of this guideline, an episode of bleeding 12 months or more after the last period is accepted as post-menopausal bleeding.
Why does it need investigation?
Post-menopausal vaginal bleeding must always be investigated. In the majority of cases no serious problem will be found, but there are times when the bleeding is the first symptom of serious disease, including cancer. Even when the bleeding is related to cancer, if it is diagnosed early there is a very good chance that the disease can be cured.
What causes PMB?
In 90% of cases examination and investigation will find either no obvious cause or a benign one. The commonest benign cause is atrophic vaginitis (inflammation of the lining of the vagina due to the lower levels of the circulating hormone estrogen at this time). Cervical and endometrial polyps are further common findings and they are usually benign. In around 10% of cases, PMB will be associated with endometrial (uterine) or cervical cancer.
Found this on obgyn website. This site is ovarian cancer, so really don't know about this, best wishes.