An International Terminology for Endometriosis, 2021.

OBJECTIVE: Different classification systems have been developed for endometriosis, using different definitions for the disease, the different subtypes, symptoms and treatments. In addition, an International Glossary on Infertility and Fertility Care has been published in 2017 by the International Committee for Monitoring Assisted Reproductive Technologies (ICMART) in collaboration with other organisations. An international working group convened over the development of a classification or descriptive system for endometriosis. As a basis for such system, a terminology for endometriosis was considered a condition sine qua non. The aim of the current study was to develop a set of terms and definitions be prepared on endometriosis that would be the basis for standardization in disease description, classification and research. DATA SOURCES: The working group listed a number of terms relevant to be included in the terminology, documented currently used and published definitions, and discussed and adapted them until consensus was reached within the working group. Following stakeholder review, further terms were added, and definitions further clarified. Although definitions were collected through published literature, the final set of terms and definitions is to be considered consensus-based. After finalization of the first draft, the members of the international societies and other stakeholders were consulted for feedback and comments, which lead to further adaptations. METHODS OF STUDY SELECTION: na TABULATION, INTEGRATION, AND RESULTS: A list of 49 terms and definitions in the field of endometriosis is presented, including a definition for endometriosis and its subtypes, different locations, interventions, symptoms and outcomes. Endometriosis is defined as a disease characterized by the presence of endometrium-like epithelium and/or stroma outside the endometrium and myometrium, usually with an associated inflammatory process. CONCLUSION: The current paper outlines a list of 49 terms and definitions in the field of endometriosis. The application of the defined terms aims to facilitate harmonization in endometriosis research and clinical practice. Future research may require further refinement of the presented definitions.