A menstrual disorder is an irregular condition in a woman's menstrual cycle.
Anovulation is absence of ovulation when it would be normally expected (in a post-menarchal, premenopausal woman). 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 (secondary amenorrhea) or excessive bleeding (dysfunctional uterine bleeding).
Polymenorrhea is the medical term for cycles with intervals of 21 days or fewer.
Metrorrhagia refers to frequent, but irregular, menstruation. If the bleeding is also heavy, it may be called menometrorrhagia.
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.
Menorrhagia is an abnormally heavy and prolonged menstrual period. If these heavy periods occur at short intervals, 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 (dysmenorrhoea).