The FIGO Ovulatory Disorders Classification System
Authors: Munro Malcolm G , Balen Adam H , Cho SiHyun , Critchley Hilary O D , Díaz Ivonne , Ferriani Rui , Henry Laurie , Mocanu Edgar , van der Spuy Zephne M ,   FIGO Committee on Menstrual Disorders and Related Health Impacts, and FIGO Committee on Reproductive Medicine, Endocrinology, and Infertility, Acharya Ganesh , Adonakis Georgios , Ahsan Sadiah , AIhaidari Taghreed , Asatiani Tengiz , Azziz Ricardo , Balen Adam , Bedard Michela , Blake Jennifer , Chamy Veronica , Cheong Ying , Cheung Vincent Y T , Cho Si Hyun , Critchley Hilary , da Silva Jose Teixeira , Diaz Ivonne , Duncan Colin , Ekersley Amelie , Epifanio-Malpassii Roberto , Famuyide Abimbola , Ferriani Rui , Giudice Linda , Gurevich Maargarita , Harlow Sioban , Hart Roger , Heikinheimo Oskari , Henry Laurie , Heylen Sulaiman , Kennedy Richard , Klepchuckova Anna , Krepelka Petr , le Roux Paul , Levchenko Kateryna , Loutradis Dimitrios , Marsh Erica , Martins Noni , Mathur Raj , Matsaseng Thabo , Miguelote Rui , Mocanu Edgar , Munro Malcolm , Ngoga Eugene , Nisolle Michelle , Norman Robert , Ono Masanori , Pintiaux Axelle , Pristauz-Telsnigg Gunda , Ramasauskaite Diana , Ravn Pernille , Reis Jose , Roos Peter , Rozic Irena , Scarella Anibal , Sharai Katsiaryna , Shibut Alena , Sierra Sony , Steiner Anne , Stoop Dominic , Toth Bettina , Van Der Spuy Zephne , Williams Saskia , Wise Lauren , Yazdani Anusch , Zhaunova Liudmila , Zunckel Meggan , Zwane Karabo 
Published: August 2022

Ovulatory disorders are common causes of amenorrhea, abnormal uterine bleeding and infertility and are frequent manifestations of polycystic ovary syndrome (PCOS). There are many potential causes and contributors to ovulatory dysfunction that challenge clinicians, trainees, educators, and those who perform basic, translational, clinical and epidemiological research. Similarly, therapeutic approaches to ovulatory dysfunction potentially involve a spectrum of lifestyle, psychological, medical and procedural interventions. Collaborative research, effective education and consistent clinical care remain challenged by the absence of a consensus comprehensive system for classification of these disorders. The existing and complex system, attributed to the World Health Organization (WHO), was developed more than three decades ago and did not consider more than 30 years of research into these disorders in addition to technical advances in imaging and endocrinology. This article describes the development of a new classification of ovulatory disorders performed under the aegis of the International Federation of Gynecology and Obstetrics (FIGO) and conducted using a rigorously applied Delphi process. The stakeholder organizations and individuals who participated in this process comprised specialty journals, experts at large, national, specialty obstetrical and gynecological societies, and informed lay representatives. After two face-to-face meetings and five Delphi rounds, the result is a three-level multi-tiered system. The system is applied after a preliminary assessment identifies the presence of an ovulatory disorder. The primary level of the system is based on an anatomic model (Hypothalamus, Pituitary, Ovary) that is completed with a separate category for PCOS. This core component of the system is easily remembered using 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. It is anticipated that, if widely adopted, this system will facilitate education, clinical care and the design and interpretation of research in a fashion that better informs progress in this field. Integral to the deployment of this system is a periodic process of reevaluation and appropriate revision, reflecting an improved understanding of this collection of disorders.