PCOS in the 2023 international guideline: seven things every student should know

Polycystic ovary syndrome is the most common endocrine disorder of reproductive-age women — the 2023 international guideline puts its prevalence at 10–13% — and one of the conditions students most often get wrong, because the teaching they received is a decade behind the evidence. The 2023 International Evidence-based Guideline, developed by an international consortium led from Monash University with dozens of professional societies, including ESHRE and ASRM, is now the reference document ^[1]. Here is what changed, and what did not.

1. The Rotterdam criteria stay — with one new option

In adults the diagnosis still requires two of three features ^[1][2]:

The new option is anti-Müllerian hormone: in adults it can replace ultrasound as the third criterion. It must not be used as a single test, and it is not recommended in adolescents.

2. If two criteria are already present, stop

A woman with irregular cycles and hyperandrogenism meets the criteria; an ultrasound or AMH adds nothing to the diagnosis. Students (and clinics) over-order the ultrasound. The scan matters only when one of the first two features is missing.

3. Ultrasound has thresholds

With a modern endovaginal transducer, PCOM means a follicle number per ovary of 20 or more and/or an ovarian volume of 10 ml or more on at least one ovary, with no corpus luteum, cysts or dominant follicles ^[1]. "Polycystic-looking ovaries" on a routine abdominal scan is not a diagnosis.

4. Adolescents are different

Within eight years of menarche the diagnosis needs both irregular cycles and hyperandrogenism. Ultrasound and AMH are not recommended at this age, because multi-follicular ovaries are normal in adolescence. Girls who have some features but not the full picture should be labelled "at risk" and reassessed later, not given a lifelong diagnosis at sixteen ^[1].

5. Always exclude the mimics

Before labelling anyone with PCOS, exclude other causes of the same picture: thyroid dysfunction (TSH), hyperprolactinaemia (prolactin) and non-classic congenital adrenal hyperplasia (17-hydroxyprogesterone). Rapid virilisation or very high androgens point to a tumour and need a different pathway.

6. PCOS is not only a fertility problem

The guideline is explicit that PCOS carries metabolic, cardiovascular and psychological risk. Recommended assessment includes weight and blood pressure, glycaemic status (an oral glucose tolerance test is preferred), a lipid profile, and screening for anxiety, depression, disordered eating and sleep apnoea. Endometrial protection matters too: cycles longer than about 90 days warrant action because of unopposed oestrogen ^[1].

7. Treatment, in order

• Lifestyle comes first for everyone, framed without weight stigma; no specific diet has been shown to be superior.
• Combined oral contraceptives are first line for irregular cycles and hyperandrogenism; no specific formulation is preferred, and lower oestrogen doses are reasonable.
• Metformin is useful for metabolic features, alone or with the pill.
• Letrozole is now first line for ovulation induction, ahead of clomiphene.
• Inositol has limited evidence and is not a substitute for the above.

Learn it with a case

The fastest way to make these points stick is a patient. MedIQ's virtual patient includes consultations built around the 2023 criteria, and the learning path covers PCOS, hyperandrogenism and anovulation step by step.