Medical Encyclopaedia › PCOS (short definition)
In brief: Polycystic ovary syndrome (PCOS) is one of the most common hormonal disorders in women of reproductive age. Typical features are irregular or absent ovulation, raised male hormones and frequently metabolic changes such as insulin resistance.
Signs
Common symptoms are irregular or absent periods, difficulty getting pregnant, increased body hair in a male pattern, acne and hair loss on the top of the head. Many of those affected are overweight, but PCOS also occurs in women of normal weight.
Causes
PCOS arises from an interplay of predisposition, hormonal control loops and metabolism. Insulin resistance increases the production of male hormones in the ovaries, which disrupts the maturation of the follicles. Many small, unruptured follicles appear as “cysts” on ultrasound – hence the name.
Diagnosis
According to the Rotterdam criteria, PCOS is diagnosed if two of three features are present: cycle disorders, raised male hormones in the blood or signs of them on the skin, and typically altered ovaries on ultrasound. Other causes, such as thyroid or prolactin disorders, are ruled out. Blood sugar and blood lipids should also be checked.
Treatment
In overweight women, even a weight loss of five to ten per cent can normalise the cycle. If pregnancy is not desired, hormonal contraceptives regulate bleeding and improve skin and hair growth. Metformin can improve metabolism. When pregnancy is desired, ovulation is usually induced with letrozole. Skin changes are treated dermatologically.
Long-term health
Women with PCOS have an increased risk of type 2 diabetes, gestational diabetes, lipid metabolism disorders, sleep apnoea and depressive moods. Regular check-ups and a healthy lifestyle are therefore important regardless of whether pregnancy is desired.
Related terms in the encyclopaedia
Ovaries, Ovulation, Insulin resistance, Hirsutism, Acne, Metformin, Infertility, Amenorrhoea
Sources
- Monash University, ESHRE, ASRM u. a.: International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome 2023
- Deutsche Gesellschaft für Gynäkologische Endokrinologie und Fortpflanzungsmedizin (DGGEF)
- IQWiG: gesundheitsinformation.de – Gesundheitsinformationen des Instituts für Qualität und Wirtschaftlichkeit im Gesundheitswesen
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.