If you have not menstruated for a year, and are therefore postmenopausal, you should no longer lose blood. A new menstruation or just a few drops of blood loss should alert you right away to see your GP. He or she will refer you for an internal ultrasound through the vulva and further tests, if necessary. Fortunately, in most cases, postmenopausal blood loss is caused by a benign cause (for example, a polyp of the endometrium) and in about half of women with postmenopausal blood loss, no cause is even found at all. However, it is important to rule out cancer of the endometrium.