Dr. Debra Richardson of the University of Texas Southwestern Medical Center in Dallas said women who have gone through menopause, for instance, should not experience any menstrual bleeding.
"Any bleeding -- even spotting -- after menopause is not normal and should be checked out by a gynecologist," Richardson said in a statement.
Some common causes of postmenopausal bleeding include:
-- Polyps are usually non-cancerous, but these growths can develop in the uterus, on the cervix or inside the cervical canal.
-- Endometrial atrophy: The tissue that lines the uterus can become very thin after menopause.
-- Endometrial hyperplasia: Sometimes the lining of the uterus becomes thick, usually due to too much estrogen and too little progesterone. Some patients may have abnormal cells that can lead to endometrial cancer.
-- Cancer: Bleeding after menopause can be a sign of endometrial or uterine cancer.