A woman is "in menopause" after she has gone for one full year without periods. So postmenopausal bleeding is any vaginal bleeding that occurs after this time. It is more common in the first one or two years of menopause. It falls off quickly to affect about 4% of women after three years.

A doctor needs to know about any postmenopausal bleeding to exclude the possibility of uterine cancer or hyperplasia, a precancerous condition. Fortunately, cancer is the cause of postmenopausal bleeding in only about 10% of women who have this symptom.

An evaluation of postmenopausal bleeding begins with an exam of the vagina and cervix to see if the blood is coming from the lower genital tract. A pelvic ultrasound is often used to check the internal organs, including the uterus, Fallopian tubes and ovaries.

The width of the uterine lining (the endometrium) is measured during the ultrasound. It should be quite thin after menopause. That's because estrogen levels are too low to stimulate growth of this tissue. If the endometrium is thick, a biopsy is used to gather cells that will be inspected under a microscope. This can determine if cancer or a noncancerous (benign) process caused the thickening.

In women not yet in menopause, estrogen is secreted by the ovaries each month to prepare the uterus for pregnancy. Estrogen levels rise in the first two weeks of a menstrual cycle to stimulate the growth, or proliferation, of the endometrium. If a pregnancy does not occur, the endometrium sheds as the menstrual period.

After menopause, the production of estrogen slows and eventually stops. Since this is a gradual and sometimes irregular process, proliferative endometrium may still be found in early menopausal women. Proliferative endometrium is a noncancerous (benign) and normal cause of thickening seen on an ultrasound.