PCOS is not a “cyst disease” – new study corrects a misconception

PCOS is one of the most common hormonal disorders affecting women and is associated with, among other things, menstrual irregularities as well as hormonal and metabolic changes. The syndrome is often linked to ovarian cysts, although the study shows this is not the case.

“In this large population-based study, women with PCOS were not found to have more ovarian cysts of any type than women without a PCOS diagnosis,” says doctoral researcher Ewelina Kuusiniemi.

The study has been published in the prestigious scientific journal JAMA Internal Medicine.

Misconception persists

The researchers believe the misunderstanding largely stems from the name of the syndrome itself. In PCOS, ultrasound examinations may reveal numerous small follicles, but these are not ovarian cysts in the true sense.

The distinction is significant: follicles are part of the normal menstrual cycle and develop towards ovulation, whereas cysts can be large fluid-filled structures that may cause symptoms and can even require surgical treatment.

“This confusion causes unnecessary concern for patients, as cysts can be painful and, in some cases, require surgical treatment, whereas the follicles associated with PCOS are not dangerous,” notes the study’s lead investigator, Professor Terhi Piltonen.

The findings may have practical implications for healthcare. They support current international guidelines stating that PCOS can be diagnosed based on symptoms and clinical findings without routine ultrasound examinations.

In other words, a PCOS diagnosis alone does not require regular ultrasound monitoring of the ovaries for cysts. This may reduce unnecessary examinations and ease the burden on healthcare services.

First study of its kind

This is the first study in the world to systematically investigate the association between PCOS and ovarian cysts. The study provides stronger population-based evidence on a topic for which only limited research data have previously been available.

The findings reinforce the view that PCOS is a hormonal and metabolic syndrome affecting the whole body, rather than simply a disorder of the ovaries.

The study is also linked to a broader international discussion concerning the name of PCOS, which many consider misleading. A new name for the syndrome is expected to be announced in the coming days. “The findings of this study are a key part of the forthcoming renaming of the syndrome,” says Professor Terhi Piltonen.

Extensive dataset of Finnish women

The study is based on the Women’s Health Study (WENDY), led by Piltonen, which is one of the world’s largest population studies focusing on women’s health.

Nearly 2,000 women aged 33–37 living in Finland took part in the study. All participants underwent a gynaecological ultrasound examination, and PCOS was defined according to the international Rotterdam criteria. The study was carried out at the University of Oulu, Oulu University Hospital and HUS.

The project was funded by, among others, the Research Council of Finland, Roche and Novo Nordisk.

Research article: Piltonen TT, Kuusiniemi E, Teede H, WENDY Research Group study group. Ovarian Cysts in Polycystic Ovary Syndrome. JAMA Intern Med. Published online May 11, 2026. doi:10.1001/jamainternmed.2026.1370