Menstruation, disorders of

An abnormality in the monthly cycle of menstrual bleeding. Menstrual disorders may be a sign of a problem in the pelvic area, such as fibroids, endometriosis, or pelvic inflammatory disease, but the cause is often unknown. Dysmenorrhoea (painful periods) is the most common type of menstrual disorder. Other types of menstrual disorder are amenorrhoea (absence of menstruation), polymenorrhoea (too frequent menstruation), oligomenorrhoea (infrequent periods or scanty blood loss), and menorrhagia (excessive bleeding). Some women have extreme variations in the length of menstrual cycles or menstrual periods, or in the amount of blood lost (see menstruation, irregular).