If your period skips for months, your cycle is erratic, or you develop unexplained acne and excess body hair, an obstetrician-gynecologist may suspect polycystic ovary syndrome (PCOS).
Despite its name, the condition does not involve true "cysts." Instead, clinicians observe numerous immature follicles—small sacs where eggs grow. Irregular ovulation can lead to menstrual dysfunction or infertility, while elevated androgen (male hormone) levels cause acne and hirsutism.
However, many women exhibit these classic symptoms yet fall short of current ultrasound-based diagnostic criteria. A new study by South Korean researchers indicates that a simple blood test measuring Anti-Müllerian Hormone (AMH) could help close this diagnostic gap.
Stricter Ultrasound Cutoffs Leave Patients in Limbo
To diagnose PCOS in adults, clinicians broadly evaluate three criteria: ovulatory dysfunction, elevated androgen levels, and polycystic ovarian morphology on ultrasound. Meeting at least two of these conditions warrants a diagnosis.
A joint research team led by Prof. Kim Jin-joo of the Department of Obstetrics and Gynecology at the Seoul National University Hospital Healthcare System Gangnam Center analyzed 118 women who were not classified as having polycystic ovarian morphology under updated ultrasound standards.
The diagnostic gap emerged not because ultrasound technology deteriorated, but because it improved. Modern high-resolution imaging makes tiny follicles far easier to detect, prompting international guidelines to raise the threshold for polycystic ovarian morphology from 12 follicles per ovary to 20 or more.
Consequently, many women presenting with irregular periods or signs of androgen excess are no longer classified as having PCOS simply because their follicle count falls just below the new 20-follicle cutoff.
AMH Blood Testing Fills Diagnostic Blind Spots
The research team focused on this overlooked patient population. Among 118 women who fell short of the new 20-follicle cutoff but met the previous 12-follicle standard, 89 (75.4%) exhibited elevated AMH levels.
AMH is secreted by small, growing ovarian follicles, and circulating blood levels naturally rise when follicle counts are high. Clinicians increasingly use AMH as a surrogate marker for polycystic ovarian morphology. While high AMH alone does not confirm PCOS, evaluating it alongside menstrual history and androgen levels allowed three out of four overlooked patients in the study to meet the full criteria for diagnosis.
Overlooked Patients Face Higher Metabolic Risks
The researchers stressed that falling short of the ultrasound threshold does not mean a patient is free from health risks.
In the study, women with elevated AMH levels displayed significantly higher waist circumferences and blood pressure compared to healthy controls, along with poorer blood glucose and cholesterol profiles. Left unmanaged, PCOS increases long-term risks for metabolic complications, including type 2 diabetes and dyslipidemia.
“We confirmed that many women who are not diagnosed based on ultrasound alone actually require active treatment and ongoing management,” said Prof. Kim Jin-joo. “Using AMH testing as a supplementary tool will allow clinicians to identify high-risk patients early and initiate timely interventions.”
She added, “We hope these findings serve as valuable clinical evidence to refine PCOS diagnostic strategies for Asian women, including South Koreans, and aid in preventing metabolic disease.”
Co-authors of the study include Prof. Lee Da-yong and Prof. Hwang Gyu-ri of Seoul Metropolitan Government–Seoul National University Boramae Medical Center, Prof. Kim Sun-mi of SNUH Gangnam Center, and Emeritus Prof. Choi Young-min of Seoul National University College of Medicine. The findings were published in the peer-reviewed international journal Reproductive BioMedicine Online.
