The power of naming disease correctly: PCOS is now PMOS

A young woman presents with irregular periods, insulin resistance, hirsutism, and difficulty losing weight. She is told she might have polycystic ovary syndrome (PCOS). She leaves the clinic and, like many patients today, turns to the Internet for answers. She searches “ovarian cysts” and quickly becomes more anxious—reading about cyst rupture, surgery, and ovarian cancer. Eventually reassured that the cysts themselves are not dangerous, she accepts a prescription for oral contraceptives and moves on with her life. The irregular cycles improve, but the underlying metabolic dysfunction remains. Years later, she develops prediabetes and continues to struggle with her mental health and body image.

The diagnosis was correct. The name was not.

PCOS has now been renamed polyendocrine metabolic ovarian syndrome (PMOS). The change, introduced in The Lancet (May 2026) and spearheaded by Professor Helena Teede of Monash University in conjunction with international societies and patient groups, reflects a contemporary understanding of this highly prevalent condition.[1]

The addition of “polyendocrine” and “metabolic” to the name signifies a paradigm shift that recognizes that PCOS has always been more than a disease of the ovaries. The new name is a clearer, more accurate description of the condition and incorporates the perspectives of clinicians and patients.[2]

PMOS affects 1 in 8 people with ovaries, making it the most common endocrinopathy in women of reproductive age. The emphasis on ovarian cysts likely came from its origin in 1935 as Stein-Leventhal Syndrome, after a series of women with amenorrhea and polycystic ovaries who were diagnosed and treated via laparotomy.[3] Although ultrasound findings of polycystic ovarian morphology became central to diagnosis in later decades, they do not represent the full pathophysiology of the condition.

The 2003 Rotterdam Criteria, which form the basis of the current diagnostic guideline, define PCOS/PMOS by two of three features:

• Oligo- or anovulation (cycles of less than 21 days or more than 35 days).
• Clinical or biochemical signs of hyperandrogenism.
• Polycystic ovaries (originally more than 12 follicles/ovary; updated in 2018 to more than 20 follicles/ovary due to improved ultrasound resolution).

Exclusion of other causes (e.g., Cushing syndrome, androgen-secreting neoplasms, congenital adrenal hyperplasia) is necessary.[3]

The most recent international evidence-based guideline for the assessment and management of PCOS[4] continues to endorse the Rotterdam Criteria but does not require ultrasound evidence of polycystic ovarian morphology to establish the diagnosis. Elevated anti-Müllerian hormone (AMH) may be used in adults as an alternative to transvaginal ultrasound when assessing ovarian morphology. This is a welcome addition to the diagnostic framework, because AMH can be measured at any point in the menstrual cycle (~$80 in BC; private pay) and is more accessible than specialized ultrasound. In adolescents (10–19 years of age), the diagnosis is made based on irregular cycles and hyperandrogenism.[1]

The diagnostic algorithms developed through the international guideline process are freely available online and provide practical guidance on diagnosis, emotional well-being, lifestyle, pharmacological treatment for nonfertility indications, infertility, and PCOS and diabetes.[5] Patient resources, including the AskPMOS app, are also available and can facilitate education and self-management.[6]

The new name—PMOS—better captures the full complexity of a condition involving insulin dysregulation, androgen excess, ovarian dysfunction, and neuroendocrine pathways. Its manifestations extend far beyond reproduction and include features that are:

• Metabolic (e.g., obesity, type 2 diabetes, cardiovascular disease, hypertension).
• Reproductive (e.g., infertility, endometrial cancer, pregnancy complications).
• Psychological (e.g., anxiety, depression, reduced quality of life).
• Dermatological (e.g., alopecia, acne, hirsutism).[1]

One of the problems with the term PCOS is that it directs attention to a feature that is neither universal nor pathological. Although more than 20 small follicles—often referred to as “ovarian cysts”—may be seen on ultrasound in women with PMOS, these are a manifestation of disrupted ovulation, not the principal cause of the disorder. The updated nomenclature reminds us to focus on the patient rather than a single imaging finding and to prioritize prevention and management of the condition’s broader health consequences.

Medicine has a long history of misleading names. Heartburn does not involve the heart, ringworm is not caused by a worm, adults can get juvenile diabetes, German measles is not measles, and endometriosis is not simply misplaced endometrial tissue. While these examples may seem amusing or harmless, terminology influences how patients understand their conditions.

A new name alone will not improve care and outcomes, but it will shift the conversation from ovarian cysts to a better appreciation of the multiple systems involved. PMOS is more than a new name; it is an opportunity to align our language with our science and ultimately improve the patient care we provide.
—Caitlin Dunne, MD, FRCSC

References

1.    Teede HJ, Khomami MB, Morman R, et al. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: A multistep global consensus process. Lancet 2026. In press. https://doi.org/10.1016/S0140-6736(26)00717-8.

2.    Monash Centre for Health Research and Implementation. PCOS has a new name and is now known as PMOS – polyendocrine metabolic ovarian syndrome. Simple patient messages. Accessed 3 June 2026. www.mchri.org.au/wp-content/uploads/2026/05/Simple-patient-message-website.pdf.

3.    Dunne C. Diagnosis and treatment of polycystic ovary syndrome (PCOS) using virtual health. This Changed My Practice (TCMP) by UBC CPD. 30 November 2022. Accessed 3 June 2026. https://thischangedmypractice.com/diagnosis-and-treatment-pcos-using-virtual-health/.

4.    Teede HJ, Tay CT, Laven J, et al. Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Hum Reprod 2023;38:1655-1679. https://doi.org/10.1093/humrep/dead156.

5.    Monash Centre for Health Research and Implementation. PCOS practice tools for health practitioners. Accessed 3 June 2026. www.mchri.org.au/guidelines-resources/health-professionals/pcos-practice-tools/.

6.    Monash Centre for Health Research and Implementation. AskPCOS app. Accessed 3 June 2026. https://mchri.org.au/guidelines-resources/community/askpcos-app/.