In this Q&A blog post, SNOMED International Chief Terminologist Dr James Case discusses SNOMED International’s response to the current international efforts to rename Polycystic ovary syndrome (PCOS), a common hormonal disorder that affects reproductive-aged women that is characterized by an imbalance of reproductive hormones and high levels of androgens, to Polyendocrine metabolic ovarian syndrome (PMOS), which better reflects its complexity. He also explores the options being considered and the timelines and process of renaming the term in SNOMED CT, and, importantly, explains how a terminology change would improve the experience and treatment of patients with the condition.
Q: There is a strong international push to rename PCOS to PMOS. Can you explain the meaning of each and the argument behind the name change?
A: Polyendocrine metabolic ovarian syndrome (PMOS), formerly known as polycystic ovary syndrome (PCOS), affects approximately one in eight women, although the true prevalence is likely higher due to underdiagnosis. The name change reflects the recognition that the condition is a complex multisystem endocrine and metabolic disorder rather than primarily an ovarian disorder. Diagnosis requires two of three features: oligo-anovulation, clinical or biochemical hyperandrogenism, and polycystic ovaries on ultrasound or elevated anti-Müllerian hormone.
The new name also addresses a long-standing source of confusion between a clinical syndrome and an anatomical finding. Polycystic ovaries are a common finding and, by themselves, do not constitute the syndrome. By shifting the focus away from ovarian morphology, PMOS more accurately reflects the underlying disease process while clearly distinguishing the syndrome from the separate finding of polycystic ovaries.
Q: How would a change in terminology contribute to better patient care and a better experience for patients?
A: A change in terminology can improve patient care by reducing misconceptions about the condition and promoting a more accurate understanding of its underlying causes. Polycystic ovaries are neither required for nor sufficient to diagnose the syndrome, yet the name Polycystic ovary syndrome can imply otherwise. Renaming the condition to Polyendocrine metabolic ovarian syndrome (PMOS) better reflects its endocrine and metabolic nature, helping patients and clinicians focus on the broader health implications of the disorder. This may support earlier recognition, more comprehensive evaluation, and better long-term management.
Q: In your post to the community, you asked for feedback on whether they agree with the name change, and you outlined the options going forward. Can you share your thoughts on how SNOMED’s editorial policy supports the change and why and whether it should or should not be changed?
A: SNOMED strives to provide the most up-to-date representation of clinical disorders; however, in many cases there is a long lag before new terminology becomes common usage in the clinical community. We frequently use international consensus publications as the justification for name changes, but we do not make those changes until we have reasonable evidence that it would be acceptable to the clinical community. A recent example was the change of the name of Diabetes insipidus to Arginine vasopressin-related polyuria. We worked with a number of endocrinologists who socialized that name change with their community prior to SNOMED making the changes. In this case, for PMOS, the consensus process was extremely robust and there has been a substantial amount of positive coverage, both in the medical literature and the lay press. SNOMED agrees with the change as it more accurately represents the nature of the condition, but wants to ensure that adopting the name at this early stage is not disruptive to the community as it requires replacement of the old concept with a new one rather than just changing the name.
Q: Can you outline the various potential approaches for the future that you proposed and the pros and cons of each?
A: The three possible approaches (there may be others) are:
No change yet — monitor usage of the term in the literature and adoption by other terminology standards, (such as ICD) before acting. This would be more retroactive than proactive, but would be in line with the adoption strategy described in the Lancet article, in which integration with SNOMED does not occur until Step 4, after broad academic dissemination and global communication.
Add PMOS as a synonym now — with preferred term status and with replacement deferred to a defined milestone such as ICD adoption or the 2028 International Guidelines update. This would make the new name available immediately without affecting existing implementations, but would not represent the new definitional characteristics, which does not correct the mischaracterization of the disorder as primarily a cystic condition.
Inactivate the existing concept and create a new PMOS concept — the editorially rigorous path, with PCOS description added as a historical synonym and appropriate replacement associations provided for implementers. The advantage to this approach is that it is a more accurate representation of the condition and retains the older term for searchability, but it impacts historical data by requiring the use of a new concept, affecting implementations. It would also require the use of historical relationships in queries to retrieve old data, making analytics more complex.
Q: What would be the timelines for each of the approaches?
A: The first option of waiting for more evidence of adoption could delay the renaming for 1-2 years, while options 2 and 3 could be implemented in SNOMED CT very quickly (weeks to months).
Q: You also asked the community for feedback on these questions:
Does the robustness of this consensus process justify early action in SNOMED CT?
Which approach best balances editorial integrity, implementer impact, and patient benefit?
What milestone should trigger full adoption if a deferred approach is preferred?
Should PCOS be retained indefinitely as an acceptable synonym or deprecated over the transition period?
What is the timeline for feedback and what are the next steps? Will you be conducting any further consultations or will you move forward based on the feedback you get?
A: We are estimating a 60-day comment period to ensure everyone has an opportunity to respond; however, if we receive overwhelming support for one option, we will adopt that one sooner. We are also reaching out to the authors of the Lancet paper to get their views on including the new name in SNOMED CT in light of their adoption strategy. We do not anticipate additional consultations as we expect a substantial number of responses given the amount of exposure that this topic has been given.
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