Chronic Endometrial Degeneration (CED): an international expert recommendation to replace the term ‘endometrosis’ in mares.

Overview

• This study aimed to replace the confusing and imprecise term “endometrosis” (used since 1992 for chronic degenerative changes in the equine endometrium) with a clearer, internationally agreed-upon term.
• An expert panel used a structured process (Delphi method) to evaluate and reach consensus on the best replacement term, ultimately recommending “Chronic Endometrial Degeneration (CED)” as the preferred nomenclature.

Background and Rationale

• “Endometrosis” has been used to describe chronic degenerative disease of the lining of the mare’s uterus (endometrium).
• The term is problematic because it sounds similar to “endometritis” (inflammation of the endometrium) and “endometriosis” (a human gynecological condition), leading to confusion.
• Accurate and clear terminology is essential for diagnosis, treatment, research, and communication within veterinary medicine.

Methodology: The e-Delphi Process

• An international panel of eight equine reproductive specialists was assembled.
• The Delphi method, a structured form of expert consensus, was conducted electronically in four rounds:
• Round 1 (Initial Evaluation): Fifteen candidate terms were rated on a 7-point Likert scale for preference and clarity. Terms with more than 50% scoring ≥4/7 were kept for next round.
• Round 2 (Refinement and Addition): Shortlisted terms plus five new terms suggested by panelists were re-evaluated with a more stringent threshold of ≥75% for retention.
• Round 3 (Consensus Vote): Six retained terms and four variations underwent forced-choice ranking, with primary criterion being ≥75% scoring ≥6/7 for consensus.
• Round 4 (Final Vote): Since no term met the 75% consensus threshold, a binary final vote was taken to determine the preferred term.

Findings and Results

• The existing term “endometrosis” was strongly rejected early on, scoring very low median ratings in Round 2 (median 1/7) and nearly unanimous opposition.
• By Round 3, “Chronic Endometrial Degeneration (CED)” scored highest with a median rating of 6/7, an interquartile range of 5-7, and 71.4% of experts rating it ≥6/7.
• All seven respondents in Round 3 ranked either CED or the similar variant “Chronic Equine Endometrial Degeneration (CEED)” as their first choice.
• In Round 4, five of eight panel members (62.5%) selected CED, making it the preferred term by majority vote.

Recommended Terminology and Implications

• The panel recommends adopting “Chronic Endometrial Degeneration (CED)” to replace “endometrosis” in:
• Equine endometrial biopsy reporting
• Clinical practice and diagnosis
• Scientific publications
• CED is favored because it is:
• Concise and clear
• Broadly descriptive, covering the degenerative nature of the condition without confusion
• Easily memorized as an acronym
• “Chronic Equine Endometrial Degeneration (CEED)” is acceptable as an alternative when species specificity is needed.
• The new terminology avoids confusion with human diseases and inflammatory conditions, improving communication among veterinarians and researchers.

Conclusion

• The study successfully used a systematic expert consensus approach to identify and recommend a clear, practical replacement for the outdated and confusing term “endometrosis.”
• The recommended term supports better clarity and precision in the understanding and management of chronic degenerative equine endometrial disease.