Excessive menstrual flow, generally an individual concept. Doctors consider the flow excessive if it causes anaemia, of which it is the commonest cause in women. There are various reasons for heavy menstruation; it often occurs in young girls in whom the menstrual pattern is not yet fixed, and in older women near the menopause. The sex hormone level in the blood is not high enough to maintain the balance between build-up and breakdown of the uterine mucous membrane. Uterine myoma, endometriosis and a fixed retroverted womb can cause the womb to be unable to contract during menstruation, leading to excessive blood loss. Overtiredness can also reduce uterine contraction; if the overtiredness is associated with anaemia, it can lead to a vicious circle. Rarer causes are coagulation problems, thyroid hormone deficiencies, congenital abnormalities of the womb, inflammation of the endometrium or polyps. Anaemia is treated in the first place, and uterine contraction can be stimulated with ergotamine tablets. If this is ineffective, a curettage can be performed, which can assist diagnosis and is in itself a treatment.