FFinalistSouthampton · 2027
Obstetrics & gynaecology
AKT · Obstetrics & gynaecology/Menstrual & benign gynae

Polycystic ovary syndrome (PCOS)

Hyperandrogenism + insulin resistance (Rotterdam criteria)

Overview

The commonest endocrine disorder in women of reproductive age. Rotterdam criteria (2 of 3): oligo/anovulation, clinical/biochemical hyperandrogenism, and polycystic ovaries on USS. Associated with insulin resistance and long-term metabolic/endometrial risk.

Recognise

  • Oligomenorrhoea/amenorrhoea, subfertility
  • Hyperandrogenism: hirsutism, acne, male-pattern hair loss
  • Obesity, acanthosis nigricans (insulin resistance)
  • USS: ≥12 follicles / increased ovarian volume

Red flags

  • Prolonged amenorrhoea → unopposed oestrogen → endometrial hyperplasia/cancer risk

Differentials & how to tell them apart

Hypothyroidism / hyperprolactinaemiacheck TFTs/prolactin — cause oligomenorrhoea
Congenital adrenal hyperplasiaraised 17-OHP, markedly high androgens
Androgen-secreting tumourrapid virilisation, very high testosterone
Cushing syndromestriae, proximal weakness, hypertension

Investigations

Bloods: raised LH (and LH:FSH ratio), raised testosterone (mildly — markedly high suggests other cause), low SHBG; exclude mimics (TFTs, prolactin, 17-OHP). Pelvic USS. OGTT/HbA1c (impaired glucose tolerance).

Management

Lifestyle/weight loss + COCP (cycle/androgen control)

  1. 1Lifestyle and weight management first-line. COCP for cycle regulation, hirsutism and endometrial protection.Gate: Give progestogen (or COCP/IUS) to induce a withdrawal bleed if amenorrhoeic → prevent endometrial hyperplasia from unopposed oestrogen
  2. 2Hirsutism: COCP ± anti-androgen (e.g. co-cyprindiol); metformin for metabolic features.
  3. 3Fertility: letrozole (or clomifene) for ovulation induction; metformin adjunct; refer.
Weight loss / lifestyle — first-line; improves all features
COCP — cycle regulation, hirsutism, endometrial protection
Metformin — metabolic features / not planning pregnancy
Letrozole (or clomifene) — first-line ovulation induction for fertility

Key points

The long-term risk is endometrial cancer from chronic anovulation (unopposed oestrogen) — ensure regular withdrawal bleeds. Letrozole is now first-line for ovulation induction.

Monitor & prognosis

Cycle, weight/metabolic (glucose, lipids, BP), endometrial protection.

Chronic; metabolic and endometrial risks manageable.

Source: NICE CKS PCOS; international PCOS guideline