What criteria should I use to diagnose Polycystic Ovary Syndrome (PCOS) in a patient presenting with irregular menstrual cycles?

When diagnosing Polycystic Ovary Syndrome (PCOS) in a patient presenting with irregular menstrual cycles, it is important to recognise that irregular menstrual cycles, specifically oligomenorrhoea or amenorrhoea, are a key clinical feature of PCOS NICE CKS.

The diagnosis of PCOS is based on established international evidence-based guidelines NICE CKS, (Legro et al. 2013), (Goodman et al. 2015). These guidelines typically consider a combination of clinical features and investigations.

• Irregular Menstrual Cycles: The presence of irregular menstrual cycles (oligomenorrhoea or amenorrhoea) is a primary indicator NICE CKS. PCOS is classified as a World Health Organization (WHO) Group 2 ovulation disorder, indicating hypothalamic-pituitary-ovarian dysfunction NICE CG156. For women with irregular cycles who are undergoing investigations for infertility, blood tests to measure serum progesterone in the mid-luteal phase and serum gonadotrophins (follicle-stimulating hormone and luteinising hormone) should be offered NICE CG156.
• Clinical Hyperandrogenism: Other clinical features that are considered in diagnosis and management include clinical hyperandrogenism, such as acne and hirsutism NICE CKS.

While the specific detailed diagnostic criteria are outlined in comprehensive guidelines from bodies such as the International PCOS Network, the European Society of Endocrinology (ESE), the Royal College of Obstetricians and Gynaecologists (RCOG) NICE CKS, the Endocrine Society (Legro et al. 2013), and the American Association of Clinical Endocrinologists, American College of Endocrinology, and Androgen Excess and PCOS Society (Goodman et al. 2015), the presence of irregular menstrual cycles alongside other clinical features like hyperandrogenism forms the basis for assessment.