Menorrhagia is the term used to describe heavy periods. Officially it is defined as passing more than an average of 80ml (about a cup full) of blood per menstrual period. Women with mennorhagia may pass blood clots during menstruation and may have menstrual accidents on their bed sheets or in their underwear. Flooding can sometimes occur when a large amount of menstrual blood gushes through the vagina suddenly on standing or during a change in position.

The causes of mennorhagia are varied. They include disorders of the blood that affect blood clotting, pelvic infections, fibroids, endometrial polyps, adenomyosis, endometriosis, endometrial hyperplasia, and pelvic cancers. When there is no obvious mennorhagia falls into the category of Dysfunctional Unterine Bleeding (DUB).