Key Facts

PCOS is a heterogeneous endocrine disorder diagnosed by the Rotterdam criteria. It is the most common cause of anovulatory infertility and is associated with significant metabolic and psychological comorbidities.

Epidemiology

• Prevalence: 8-13% of women of reproductive age (varies by diagnostic criteria and population)
• Up to 70% of affected women remain undiagnosed
• Onset typically around puberty/early adulthood
• Higher prevalence in South Asian women

Aetiology

• Genetic: strong familial component; polygenic inheritance
• Environmental: obesity amplifies clinical features; diet and lifestyle factors
• Insulin resistance: present in 50-70% of women with PCOS (independent of BMI)

Pathophysiology

• Hyperinsulinaemia stimulates ovarian androgen production and reduces SHBG (increasing free androgens)
• LH hypersecretion from the pituitary (raised LH:FSH ratio >2:1) drives thecal cell androgen production
• Arrested follicular development: multiple small antral follicles fail to mature, resulting in anovulation
• Androgen excess: causes hirsutism, acne, and alopecia
• Chronic anovulation: leads to unopposed oestrogen exposure → endometrial hyperplasia risk

Menstrual Disturbance

• Oligomenorrhoea (cycles >35 days) or amenorrhoea
• Irregular, unpredictable periods
• Heavy withdrawal bleeds

Hyperandrogenism

• Hirsutism (Ferriman-Gallwey score ≥8): face, chest, abdomen, thighs
• Acne (particularly adult-onset persistent acne)
• Androgenic alopecia (temporal recession, crown thinning)

Metabolic Features

• Obesity (50-70% of PCOS patients, typically central/android)
• Acanthosis nigricans (marker of insulin resistance)
• Impaired glucose tolerance or type 2 diabetes

Red Flags

• Rapid onset virilisation (deepening voice, clitoromegaly): exclude androgen-secreting tumour
• Cushing's features: exclude hypercortisolism
• Galactorrhoea: exclude hyperprolactinaemia
• Amenorrhoea >6 months with no withdrawal bleed: assess endometrium for hyperplasia

Bedside

• BMI, waist circumference
• Blood pressure
• Ferriman-Gallwey scoring (hirsutism assessment)
• Acanthosis nigricans examination

Bloods

• Total testosterone: elevated (usually <5 nmol/L; if >5 consider tumour)
• SHBG: low (increases free androgen index)
• LH and FSH: LH:FSH ratio >2:1 (supportive but not diagnostic)
• TFTs: exclude thyroid disease
• Prolactin: exclude hyperprolactinaemia
• 17-hydroxyprogesterone: exclude late-onset CAH (early morning sample)
• Fasting glucose and HbA1c: screen for diabetes/pre-diabetes
• Lipid profile: metabolic screening
• OGTT: recommended if BMI >30 or other risk factors for diabetes

Imaging

• Pelvic USS (TVS): polycystic morphology = ≥12 follicles (2-9mm) per ovary or ovarian volume >10 mL
• Note: USS criteria are not required if oligo/anovulation and hyperandrogenism are both present

Special Tests

• DEXA scan if prolonged amenorrhoea (osteoporosis risk)
• Endometrial biopsy if prolonged amenorrhoea (>3 months) to exclude hyperplasia

Non-pharmacological

• Lifestyle modification is the cornerstone: 5-10% weight loss can restore ovulation and improve metabolic parameters
• Diet: calorie restriction, low glycaemic index diet
• Exercise: 150 minutes/week moderate intensity
• Psychological support for body image, anxiety, depression

Pharmacological

• Menstrual regulation:
  • COC pill (e.g. Dianette: co-cyprindiol contains cyproterone acetate as anti-androgen)
  • Cyclical progestogens (medroxyprogesterone 10mg for 14 days every 1-3 months) to prevent endometrial hyperplasia
  • Mirena IUS for endometrial protection
• Anti-androgen therapy:
  • Co-cyprindiol (Dianette) for 3-6 months (review VTE risk)
  • Spironolactone 25-100mg OD (off-label; requires contraception - teratogenic)
  • Finasteride 5mg OD (off-label; teratogenic)
• Metabolic management:
  • Metformin 500mg TDS (titrate slowly; off-label for PCOS; improves insulin sensitivity)
• Infertility:
  • Letrozole 2.5mg OD days 2-6 (first-line ovulation induction; international guidelines)
  • Clomifene 50-150mg OD days 2-6 (NICE NG156)
  • Gonadotrophins (low-dose step-up protocol) if resistant
  • Laparoscopic ovarian drilling as second-line surgical option

Surgical/Interventional

• Laparoscopic ovarian drilling (LOD): electrocautery/laser to ovarian surface; induces ovulation in 50-80%
• Bariatric surgery: consider if BMI >40 (or >35 with comorbidities)

Referral Criteria

• Infertility: refer to reproductive medicine after 12 months (or 6 months if age >35)
• Rapid virilisation or testosterone >5 nmol/L: urgent gynaecology/endocrine referral
• Mental health support if needed
• Endocrinology referral for complex metabolic management

• PCOS is a lifelong condition but symptoms often improve with weight loss and age
• Type 2 diabetes risk: 5-10× higher; annual screening recommended
• Cardiovascular disease risk: 2× higher (dyslipidaemia, hypertension)
• Endometrial cancer risk: 2-6× higher due to chronic anovulation and unopposed oestrogen
• Obstructive sleep apnoea: 5-30× more common in women with PCOS
• Fertility: most women with PCOS achieve successful pregnancy with treatment (70-80% ovulation rate with letrozole/clomifene)
• Pregnancy complications: increased risk of GDM (3×), pre-eclampsia (3-4×), preterm birth

Rotterdam Diagnostic Criteria

Metabolic Screening in PCOS