Opposed to amenorrhoea is menorrhagia, or an excessive menstrual flow. Metrorrhagia, or hemorrhage from the uterus at any time, is a term confounded with menorrhagia, which is an inordinate menstrual loss of uterine blood, but the distinction is not important. Menorrhagia and metrorrhagia commonly have an identical cause and they frequently coexist. They are found in chronic diseases of the heart, lungs, liver, and other organs; they are an outcome of prolonged lactation, and of local affections of the uterus and its appendages. Any condition also that deranges the blood may cause menorrhagia or metrorrhagia; so do malignant tumours of the uterus, uterine displacements, lacerations that {242} occur in childbirth, and psychical influences, as fright, anxiety, and other strong emotions. Dysmenorrhoea, difficult or obstructed menstruation, is a term used for menstruation accompanied by pain. This is a common menstrual derangement, and it may be neuralgic or inflammatory in origin, or it may be caused by obstruction to the menstrual flow. There is another variety of dysmenorrhoea, called membranous, in which the superficial layer of the uterine lining is cast off partly or wholly. In the neuralgic form the uterus and its appendages are normal in appearance, but the pain recurs monthly, and it may have degrees from mere discomfort to agony. This form is characterised by reflex headache, sympathetic nausea or vomiting; and the pain may not be confined to the uterus and its appendages. The irritation often brings out latent hysterical phenomena, spinal irritation, and neurasthenia. Rheumatism and gout are predisposing causes, so are indolence, lack of physical exercise, light clothing in cold weather, forced school work and similar depressing agents. In the neurotic variety of dysmenorrhoea pain often persists after the menstrual flow has set in, but in inflammatory dysmenorrhoea the flow relieves the pain or removes it. Marriage commonly removes the neurotic form of dismenorrhoea. In obstructive dysmenorrhoea the menstrual fluid is retained by narrow or tortuous outlets, flexions of the uterus, and similar causes. The prognosis is good in all forms of dysmenorrhoea, but frequently long and skilful treatment is required to cure such conditions, especially the membranous form. Inflammatory, obstructive, and membranous dysmenorrhoea are commonly made worse by marriage.