The FIGO ovulatory disorders classification system

Abstract

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 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 manuscript 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.

Keywords: anovulation; ovulatory disorders; ovulatory disorders classification; ovulatory dysfunction.

Figure 1

Participants by region, displayed as a percentage. Note: While there was representation from every region, Europeans comprised the majority.

Figure 2

Participants by age and gender. Note: The proportion of men versus women and the age distribution are displayed.

Figure 3

Participants by stakeholder representation. Note: Almost 60% of the participants represented national obstetrical and gynecological societies, while 19% were deemed “Experts at large” based primarily on their contributions to the scientific literature. Journal and subspecialty representatives each comprised 9% of the participant pool.

Figure 4

Participants' roles in their local institution or organization. Note: Each participant was asked to reveal their primary (left) and secondary (right) roles or responsibilities in their local institution or organization. Almost three‐quarters were primarily involved in clinical care, and there were no individuals who reported that bench research or editorial activity was their primary role. More than one‐third saw clinical research as their secondary role, while almost one‐quarter reported teaching as their secondary responsibility.

Figure 5

Graphical depiction of the proposed FIGO Ovulatory Disorders Classification System. Note: After the individual is diagnosed with an ovulatory disorder, the core or first level of the system is the allocation to type I, II, or III disorders according to their presumed primary source: hypothalamus, pituitary gland, or ovary, respectively. PCOS comprises the type IV category and the criteria proposed by WHO are to be used to determine this categorization. The second level stratifies each anatomic category (types I–III) into the known or presumed mechanism according to the “GAIN‐FIT‐PIE” mnemonic as appropriate and applicable. Abbreviation: PCOS, polycystic ovary syndrome.

Figure 6

Disorders of ovulation exist on a spectrum that ranges from occasional failure to ovulate to chronic anovulation. Note: Typically, but not always, these disorders manifest abnormalities in menstrual parameters such as frequency, regularity, duration, and volume of bleeding, and, in the case of chronic anovulation with amenorrhea. It is apparent that the luteinized unruptured follicle (LUF) and luteal out of phase (LOOP) disorders exist on a similar spectrum of varying frequency.