Experts Say The Old PCOS Name Misled Millions Of Patients For Decades

One of the world’s most common hormone disorders has officially been renamed in a move experts hope will end decades of confusion and stigma. Polycystic ovary syndrome, long known as PCOS, is now being redefined as polyendocrine metabolic ovarian syndrome, or PMOS.

The change was announced at the European Congress of Endocrinology in Prague following 14 years of work involving clinicians, researchers, and patient advocates. The international consortium behind the effort argues that the old name was not only inaccurate but may also have contributed to poor understanding and delayed care.

Why The Old PCOS Name Failed

The renaming initiative was jointly led by advocacy group Verity, Monash University in Australia, and the Androgen Excess and PCOS Society. In a published policy paper, the groups argue that focusing on “ovary” and “cysts” obscured the condition’s much broader hormonal and metabolic effects.

Researchers note that PCOS referred to just one organ, despite the syndrome affecting multiple endocrine systems and influencing the brain, skin, metabolism, body weight, and mental health. Many patients reported that this narrow focus contributed to delayed diagnoses and widespread misconceptions.

Patient advocate Lorna Berry, who lives with PMOS and participated in the project, said she hopes the new terminology will improve long-term care and recognition. She described years of struggling to have her symptoms taken seriously and later facing misinformation even after diagnosis.

The Myth Of Ovarian “Cysts”

The “cystic” description dates back to 1935, when Chicago surgeons Irving Stein and Michael Leventhal described women with enlarged ovaries containing multiple small cyst-like structures. Removing some of this tissue appeared to restore menstrual cycles and fertility in certain patients.

At that time, scientific understanding of ovulation and sex hormones such as estrogen and progesterone was still limited. By 1958, Stein had begun referring to the disorder as Stein-Leventhal syndrome, which eventually evolved into the term PCOS.

Modern imaging has since demonstrated that these supposed cysts are actually immature ovarian follicles that stopped developing normally. Many people with PMOS do not show this pattern at all, and when it is present, surgery is rarely needed, undermining the central premise of the old name.

Finnish obstetrician-gynecologist Terhi Piltonen, who contributed to the global naming policy, describes PCOS as a misleading term. She says many patients—and even some healthcare professionals—mistakenly believed the ovaries contained dangerous cysts that could rupture or require removal.

In reality, PMOS is often characterized by ovaries with a high reserve of small follicles. According to Piltonen, the excessive focus on cysts caused many clinicians to overlook metabolic complications, weight-related issues, psychological distress, and skin symptoms.

A Multisystem Syndrome, Not Just Fertility

PMOS can cause irregular menstrual cycles, disrupted ovulation, excess facial or body hair, acne, and infertility. However, researchers emphasize that the condition extends far beyond reproductive health and ovarian function.

Evidence suggests PMOS may involve complex brain-hormone interactions and long-term endocrine disruption. Anxiety, depression, and other psychological challenges are also more common, alongside dermatological symptoms such as severe acne and hair thinning.

Symptoms frequently continue well beyond reproductive age, affecting quality of life into menopause and later life. Advocates say this lifelong impact was one of the main reasons for adopting a name that reflects broader hormonal and metabolic dysfunction.

Globally, PMOS is estimated to affect around 170 million people, making it one of the world’s most common endocrine disorders. Despite this prevalence, studies suggest up to 70 percent of cases remain undiagnosed.

Metabolic Risks Often Go Unrecognized

Adding the word “metabolic” to the new name is considered one of the most important changes. Research indicates that up to 85 percent of people with PMOS experience insulin resistance, meaning the body becomes less effective at using insulin properly.

This significantly increases the risk of type 2 diabetes, obesity, and non-alcoholic fatty liver disease. Cardiovascular risk factors such as high blood pressure and unhealthy cholesterol levels are also more common.

Yet many patients are not routinely screened for these problems because the previous PCOS label focused heavily on fertility and gynecological symptoms. Experts hope the PMOS terminology will encourage more comprehensive metabolic evaluation and monitoring.

Polish endocrinologist Blazej Meczekalski has argued that the PCOS label is misleading and reinforces negative stereotypes about patients. He notes that research priorities have increasingly shifted from reproduction alone toward metabolic health and long-term disease prevention.

Implications For Treatment And Policy

There is currently no single known cause or cure for PMOS, and treatment typically focuses on managing individual symptoms. Therapies may include hormonal contraceptives, anti-androgen medications, lifestyle interventions, fertility treatment, and, in some cases, surgery.

Metformin, a widely used diabetes medication, has also become an important off-label treatment for PMOS. A landmark randomized, double-blind, placebo-controlled trial published in 2000 found that metformin reduced insulin and testosterone levels, helping improve some core features of the syndrome.

Since then, evidence supporting metformin and other metabolic therapies has expanded considerably. However, because these treatments are not formally approved for PMOS in many countries, patients may still face significant out-of-pocket expenses.

Advocates argue that emphasizing the metabolic nature of the condition in its new name could improve regulatory recognition, insurance coverage, and investment in targeted therapies. It may also encourage clinical guidelines that prioritize diabetes and cardiovascular screening.

How The Transition Will Work

The consortium recommends that healthcare professionals and researchers use PMOS alongside PCOS during a three-year transition period. The goal is to educate patients, clinicians, and policymakers while reducing confusion during the shift.

One major objective is persuading international classification systems to formally adopt the new terminology, including the World Health Organization’s International Classification of Diseases (ICD), which is used by 195 countries to code diagnoses and shape healthcare policy.

If the WHO eventually adopts the updated terminology, PMOS would likely become the global standard in medical records, research, and insurance systems. Advocates believe this would represent a major step away from decades of misunderstanding and toward more comprehensive care.

The proposal and implementation strategy were published in The Lancet, alongside calls for better education, earlier diagnosis, and improved access to evidence-based treatment. For millions of patients worldwide, supporters say the name change could mark the beginning of a new era in understanding and care.