As you can tell from the responses there are many reasons someone can bleed after menopause. The most important thing is to have an exam/evaluation through the details of your medical history and identify the source/rule out more serious reasons for bleeding. One common reason can be thinning of the vaginal tissue due to low estrogen levels (vaginal atrophy). This is a relatively simple condition which can be managed with some form of vaginal estrogen treatment.

The more concerning scenario is if your bleeding is coming from the uterus due to abnormal thickening of the uterine lining (endometrium). Your provider can either perform an ultrasound to measure the endometrial thickness or they can perform an endometrial biopsy to get a tissue sample. Any woman with post-menopausal bleeding should be seen to rule out any physical process that could be endometrial cancer or precursor (e.g. endometrial hyperplasia). Bleeding from the uterus can also be related to a very thin endometrial lining similar to what happens in the vagina (endometrial atrophy). During your exam they can visualize the cervix and make sure it looks normal and make sure your pap smear is up to date.

Majority of the time people have post-menopausal bleeding for simple conditions that can easily be managed, however your physician's job is to rule out the more complicated things and make sure you are safe and healthy.