Figure 6.

Classification of ovulatory disorders according to the International Federation of Gynecology and Obstetrics—FIGO (A) [162] and the World Health Organization—WHO (B) [163,164]. The primary level of the FIGO system is based on an anatomic model (hypothalamus, pituitary, ovary) that is completed with a separate category for polycystic ovary syndrome (PCOS; the acronym HyPO-P). Each anatomic category is stratified in the second layer of the system to provide granularity for investigators, clinicians, and trainees using the “GAIN-FIT-PIE” mnemonic (genetic, autoimmune, iatrogenic, neoplasm; functional, infectious and inflammatory, trauma and vascular; physiological, idiopathic, endocrine). The tertiary level allows for specific diagnostic entities, including those related to PCOS.