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Women's Health

Polycystic ovary syndrome

Polycystic ovary syndrome is a heterogeneous endocrine, metabolic and reproductive condition characterised by ovulatory dysfunction and hyperandrogenism, with polycystic ovarian morphology in some people; diagnose by the appropriate criteria, exclude mimics and manage reproductive, metabolic, psychological and endometrial risks together.

In a nutshell

PCOS is diagnosed in adults by two of three domains—ovulatory dysfunction, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology—after mimics are excluded. Manage cycle and endometrial risk, hyperandrogenism, metabolic and psychological health, and fertility as linked but distinct priorities.

Classic presentation

Infrequent or absent periods with hirsutism, acne, androgenic alopecia or subfertility, with possible dysglycaemia, sleep-apnoea symptoms or psychological distress; obesity and polycystic ovaries are not required.

Key points

  • Adult diagnosis requires two of three domains: oligo/anovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology, after excluding mimics.
  • If irregular cycles and hyperandrogenism are both present, ultrasound or AMH is not needed; an isolated polycystic ovarian appearance does not diagnose PCOS.
  • Do not use LH:FSH ratio as a diagnostic test. Rapid virilisation or severe androgen excess needs an alternative diagnosis pathway.
  • Assess glycaemic status, blood pressure, lipids, sleep, mental health and eating-disorder risk; repeat surveillance according to individual risk.
  • For people not trying to conceive, use an appropriate hormonal or progestogen strategy for cycle control and endometrial protection, with current BNF safeguards.
  • When anovulatory infertility is due to PCOS, letrozole is the current first-line option in the 2023 international guideline; fertility specialists monitor escalation and pregnancy risk.

First-line investigation

History and examination for ovulatory dysfunction and hyperandrogenism, targeted exclusion of mimics, and metabolic risk assessment; use adult ultrasound or AMH only when the ovarian-morphology domain is needed.

Management

Confirm the pattern and exclude mimics

  • Assess cycle pattern, clinical and biochemical hyperandrogenism, pregnancy and alternative endocrine causes; apply adult or adolescent criteria appropriately.1,2,3

Support health and protect the endometrium

  • Offer stigma-free lifestyle and wellbeing support to everyone, and use a suitable combined hormonal or progestogen strategy for cycle control and endometrial protection when pregnancy is not being pursued.1,3,2,7

Treat metabolic and psychological risk

  • Assess glycaemia, blood pressure, lipids, sleep and mental health, then manage diabetes, cardiovascular risk, sleep apnoea, depression, anxiety or disordered eating through the relevant pathways.1,3,5,2

Address hirsutism and fertility goals

  • Use cosmetic and hormonal strategies for hirsutism with contraception and BNF safeguards for anti-androgens; refer for fertility care and consider letrozole first-line for PCOS-related anovulatory infertility under specialist monitoring.1,6,3,2,7

Review long-term health and bleeding

  • Offer coordinated annual review or earlier review for symptoms and risk, and investigate persistent, heavy or post-amenorrhoea bleeding rather than relying on a fixed screening threshold.3,1,8,4

Exam traps

  • Polycystic ovaries are not the same as PCOS: morphology alone is insufficient, and ultrasound is unnecessary when irregular cycles and hyperandrogenism already establish two adult domains.
  • LH:FSH ratio is not a Rotterdam criterion and should not be used to diagnose or exclude PCOS.
  • PCOS can occur in a person with a normal BMI, regular-looking ovaries or no obvious insulin resistance.
  • Rapid-onset virilisation is not typical PCOS; consider an androgen-secreting tumour or another endocrine disorder.
  • Do not leave prolonged amenorrhoea without endometrial protection or safety-netting, but do not offer routine endometrial screening to asymptomatic people.
  • NICE's dedicated UK PMOS guideline is still in consultation in 2026; current fertility recommendations must be checked live rather than copied from older NICE PCOS guidance.

Illustrations

Insulin and androgen pathwayDiagram showing how variable insulin resistance and hyperinsulinaemia can amplify ovarian androgen production and reduce SHBG, while making clear that insulin resistance is common but not required for the diagnosis.PassFinals · original
Adult diagnostic domainsVenn diagram showing ovulatory dysfunction, clinical or biochemical hyperandrogenism and polycystic ovarian morphology, with adult diagnosis requiring two domains after exclusion of mimics; include a warning that adolescent criteria differ.PassFinals · original
Polycystic ovarian morphologyUltrasound image showing multiple small antral follicles, labelled as follicular morphology rather than true ovarian cysts and accompanied by the reminder that morphology alone does not diagnose PCOS.Schomynv, Wikimedia Commons · CC0

Key sources

  1. NICE CKS: Polycystic ovary syndrome (Current UK primary-care topic used for diagnosis, exclusion of mimics, symptom management, metabolic risk and endometrial protection; access may require NHS or professional login.)
  2. International evidence-based guideline for assessment and management of PCOS 2023 (Multidisciplinary evidence-based guideline used as an interim detailed source because the dedicated UK NICE PMOS guideline is still in development; includes adult and adolescent diagnosis, AMH, metabolic risk, psychological care, lifestyle, hirsutism and fertility recommendations.)
  3. NICE GID-NG10436: Polyendocrine metabolic ovarian syndrome draft guideline (UK draft consultation guidance expected to publish in December 2026. It adapts the 2023 international guideline to the UK context; it is recorded here as a current draft and must not be treated as final guidance.)
  4. RCOG: Polycystic ovary syndrome and long-term health (UK Royal College of Obstetricians and Gynaecologists information on reproductive, metabolic and longer-term health effects of PCOS.)
  5. NICE NG128: Type 2 diabetes in adults: management (Current NICE diabetes pathway used when PCOS-related screening identifies prediabetes or type 2 diabetes.)
  6. NICE NG257: Fertility problems: assessment and treatment (Current NICE fertility guidance published 31 March 2026. The former PCOS-specific ovulation-disorder recommendations were removed while NICE develops the dedicated PMOS guideline; use this source for general fertility assessment and gonadotrophin safety requirements.)
  7. BNF online: current hormonal, metabolic and fertility prescribing information (Use the current BNF and local fertility or endocrine protocol for combined hormonal contraception, progestogens, metformin, anti-androgens, ovulation induction, pregnancy contraindications, monitoring and doses; no fixed dose is reproduced here.)
  8. NICE NG12: Suspected cancer: recognition and referral (Current NICE suspected-cancer pathway used when persistent, heavy, intermenstrual or post-amenorrhoea bleeding needs urgent endometrial assessment.)
  9. NICE NG3: Diabetes in pregnancy (Current NICE pregnancy guidance used for pre-existing or gestational diabetes risk, pregnancy planning and antenatal care when a person with PCOS is pregnant or has diabetes.)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.