From a positive perspective, bleeding during menstruation means that a woman is getting enough estrogen into the body to achieve a tissue effect. In other words, monthly menstruation tells us that the medication is actually working.
One of the revolutions in modern gynecology is transvaginal ultrasound. This enables the gynecologist to actually see what is happening within the uterus. This is a simple and totally painless diagnostic procedure where sound (similar to sonar) is used to examine the contents of the uterus. A thin uterine lining (less than 5 mm) is never associated with uterine cancer. When there is a thickening of the cavity (more than 5 mm) an endometrial biopsy is done. With the advent of new diagnostic technologies it is very easy to diagnose diseases that occur in the faulty uterus.
If you're past menopause and haven't had a period for several months -- then start having minor bleeding once a month or so -- you should probably see a doctor.
When a woman is in perimenopause -- usually during her 40s -- it's normal to skip one period and have one the next month. Post menopausal bleeding is always not cancerous, but it is a cause of concern. We really have to watch it…we are lucky with uterine cancer in that there is always bleeding and there fore we can catch it early. Never hesitate to consult a gynecologist if you have a suspicious bleeding.