A menstrual disorder is an irregular condition in a woman's menstrual cycle.
Disorders of ovulation include oligoovulation and anovulation. Oligoovulation is infrequent or irregular ovulation (usually defined as cycles of more than 36 days or less than 8 cycles a year) Anovulation is absence of ovulation when it would be normally expected. Anovulation usually manifests itself as irregularity of menstrual periods, that is, unpredictable variability of intervals, duration, or bleeding. Anovulation can also cause cessation of periods or excessive bleeding.
Disorders of cycle length include polymenorrhea, irregular menstruation, metrorrhagia, oligomenorrhea and amenorrhea. Polymenorrhea is the medical term for cycles with intervals of 21 days or fewer. Irregular menstruation is where there is variation in menstrual cycle length of more than approximately eight days for a woman. The term metrorrhagia is often used for irregular menstruation that occurs between the expected menstrual periods. Oligomenorrhea is the medical term for infrequent, often light menstrual periods (intervals exceeding 35 days). Amenorrhea is the absence of a menstrual period in a woman of reproductive age. Physiologic states of amenorrhoea are seen during pregnancy and lactation (breastfeeding). Outside of the reproductive years, there is absence of menses during childhood and after menopause.
Disorders of flow include hypomenorrhea, menometrorrhagia, and menorrhagia. Hypomenorrhea is abnormally light menstrual periods. Menorrhagia is an abnormally heavy and prolonged menstrual period. If there is excessive menstrual and uterine bleeding other than that caused by menstruation, menometrorrhagia may be diagnosed. Causes may be due to abnormal blood clotting, disruption of normal hormonal regulation of periods or disorders of the endometrial lining of the uterus. Depending upon the cause, it may be associated with abnormally painful periods called dysmenorrhea. Dysmenorrhea, cramps or painful menstruation, involves menstrual periods that are accompanied by either sharp, intermittent pain or dull, aching pain, usually in the pelvis or lower abdomen.