A normal menstrual cycle can be divided into follicular and luteal phases. It may last from 21 to 35 days, with an average duration of 28 days, while the follicular phase lasts on average 14–21 days, and the luteal phase about 14 days. Variability of the cycle is relatively little between 20 and 40 years, while 5–7 years after menarche and about 10 years before menopause increase in variability is observed. Menstrual disorders can be divided according to (Dunaif et al. Fertil Steril. 86(5):S148-55, 2006): Other classifications of abnormal menstrual bleeding are the WHO classification and FIGO PALM-COEIN classification. Classification of menstrual disorders is according to the World Health Organization (WHO), 1976. According to this classification, disorders are divided into seven groups based on the etiopathogenesis: hypothalamic-pituitary insufficiency, hypothalamic-pituitary axis dysfunction, primary ovarian insufficiency, congenital malformations and acquired defects of the uterus, prolactin-producing hypothalamic-pituitary tumors, hypothalamic-pituitary axis dysfunction combined with hyperprolactinemia, post-traumatic or post-inflammatory tumors, and hypothalamic-pituitary gland damage. Other mentioned classification is the FIGO PALM-COEIN classification. It is not restricted to just menstrual bleeding that was abnormally heavy, but also includes bleeding that was abnormal in timing. Additionally, the terms “dysfunctional uterine bleeding (DUB)” and “menorrhagia” were withdrawn. PALM COEIN divides uterine bleedings into three categories: chronic, acute, and intermenstrual. PALM-COEIN is an acronym arranged into nine main categories of AUB. Those categories are, respectively, polyp, adenomyosis, leiomyoma, malignancy and hyperplasia, coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, and not yet classified.