Polycystic ovary syndrome (PCOS)

Definition

Rotterdam Criteria

• First criterion: oligo- and/or anovulation.
• Second criterion: clinical and/or biochemical hyperandrogenism.
• Third criterion: polycystic ovaries (ultrasound).
• What is additionally required: exclusion of other causes (diagnosis of exclusion).
• In adolescents in the first few years after menarche: ultrasound criterion does not apply.

Clinical features

What Belongs to PCOS but Is Not in the Criteria

• Pathogenetically central: insulin resistance with hyperinsulinaemia.
• Further risks: dyslipidemia, hypertension, fatty liver.
• Long-term gynaecological risk: endometrial hyperplasia to carcinoma.

Differentiating the Terms

• Hirsutism: terminal hair at androgen-dependent sites.
• Hypertrichosis: androgen-independent hair growth, often drug-induced.
• Virilisation: hirsutism plus clitoromegaly, voice deepening.
• How hirsutism is graded: using the Ferriman-Gallwey score (9 body regions).
• What rapid progression with virilisation means: suspicion of androgen-producing tumor (urgent workup!).

Diagnosis

Ovary on Ultrasound

• Follicle count criterion according to current definition: ≥ 20 follicles (2–9 mm) per ovary.
• Alternative criterion: ovarian volume > 10 ml (without follicle/corpus luteum).
• Typical distribution of follicles: string of pearls, subcapsular.
• Important clarification: PCO alone is not a syndrome.

Laboratory Findings and Their Interpretation

• Tests performed: testosterone, SHBG, FAI, DHEAS, LH, FSH, E2, PRL, TSH.
• Classic but not mandatory constellation: elevated LH-FSH ratio.
• Where ovarian androgens are produced: in the theca cells.
• Where DHEAS originates: from the adrenal cortex.
• What a markedly elevated testosterone necessitates: ruling out an androgen-producing tumour/CAH.
• Why AMH is often high: many small follicles produce AMH.

Keep learning in the app

Further reading (selection)

1. StatPearls: Polyendocrine Metabolic Ovarian Syndrome (NCBI Bookshelf)
2. DocCheck Flexikon, Polyzystisches Ovarialsyndrom
3. DocCheck Flexikon, Hirsutismus

Cross-references