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  3. Polycystic Ovary Syndrome (PCOS)

Polycystic Ovary Syndrome (PCOS)

NICE CKS Polycystic ovary syndrome. Last revised: Mar 2025. NICE Clinical guideline [CG156] Fertility problems: assessment and treatment. Last updated: Sep 2017.

Guidelines

PCOS can be diagnosed if at least 2 of the following are present (Rotterdam criteria):
 

Category Description
Ovulatory dysfunction Manifested as oligomenorrhoea / amenorrhoea
Hyperandrogenism (clinical and/or biochemical evidence) Clinical evidence:
  • Hirsutism (alone is predictive of biochemical hyperandrogenism)
  • Acne
  • Female pattern hair loss

See blood tests section (below) for biochemical evidence
Supportive ultrasound findings ≥20 follicles in at least 1 ovary
 
 

NICE CKS notes that in adolescent girls, both irregular menstrual cycles and hyperandrogenism are required to diagnose PCOS.

Measure the following to help diagnose PCOS:
 

Test

Interpretation

Total testosterone

↑ (only moderately raised, if significantly raised other causes of hyperandrogenism are more likely)

SHBGSex hormone binding globulin

↓

Free androgen index

↑



Measure the following to exclude other causes of oligomenorrhoea and amenorrhoea:
 

Test

Purpose

LH and FSH

Exclude premature ovarian failure

↑ LH:FSH ratio is supportive of PCOS (no longer recommended to guide diagnosis, but common in exams). However, note that ↑ FSH suggests ovarian insufficiency

Prolactin

Hyperprolactinaemia can cause subfertility and menstrual disturbances

TSH

Hyperthyroidism and hypothyroidism can cause menstrual disturbances

All patients:
  • Encourage a healthy lifestyle
  • Optimise weight management
  • Assess for and manage cardiovascular risk factors (e.g. hypertension, type 2 diabetes, dyslipidaemia, smoking cessation)

Apart from the above lifestyle management, subsequent management depends on whether the patient wants to become pregnant.
 

1st line:​​​​​​
  • COCPCombined oral contraceptive pill - all patients (if no contraindications)
  • Metformin - if BMI ≥25 kg/m2 

Treatment for specific features:
  • Acne - see this article
  • Hirsutism - hair reduction and removal (e.g. shaving and waxing)

If there is prolonged amenorrhoea (<1 period every 3 months) or abnormal vaginal bleeding:
  • Give cyclical progesterone to induce a withdrawal bleed, then refer for transvaginal ultrasound to assess endometrial thickness
 
  • If endometrial thickness >10mm / unusual appearance → endometrial sampling
  • If normal endometrium → treatment to prevent endometrial hyperplasia (cyclical progestogen / low-dose COCP / LNG-IUD)

If BMI ≥30: 
  • 1st line: attempt losing weight (weight loss alone may already restore ovulation)
  • Weight loss also improves response to ovulation induction agents and have +ve impact on pregnancy outcomes

1st line ovulation induction:
  • Clomifene citrate, and/or
  • Metformin

2nd line ovulation induction:
  • Clomifene + metformin (if not already offered), or
  • Gonadotrophins, or
  • Laparoscopic ovarian drilling
 
 

For those who take clomifene citrate:

  • Offer ultrasound monitoring during at least 1st cycle of treatment to ensure the lowest effective dose (due to risk of multiple pregnancy and ovarian hyperstimulation syndrome)
  • Do not continue treatment for >6 months

References

Author: Adams Lau
Reviewer:
Last edited: 12/08/25