Rotterdam Criteria (2003)
International standard for PCOS diagnosis
What it is
The Rotterdam criteria are the international standard for diagnosing polycystic ovary syndrome (PCOS). They were established in 2003 at a joint consensus between ESHRE (European Society of Human Reproduction and Embryology) and ASRM (American Society for Reproductive Medicine).
PCOS is diagnosed when at least 2 of 3 criteria are present, after excluding other conditions that could explain the symptoms.
The 3 Rotterdam criteria
Criterion 1 — Oligo-anovulation
Irregular cycles (oligo-ovulation) or absent cycles (anovulation). In practice: fewer than 8 cycles per year, or cycles of highly variable length (> 35 days).
Criterion 2 — Clinical or biochemical hyperandrogenism
Either clinical: hirsutism assessed by the Ferriman-Gallwey score > 4-6, severe acne, androgenic alopecia. Or biochemical: elevated total or free testosterone, elevated DHEA-S or androstenedione.
Criterion 3 — Polycystic ovarian morphology (PCOM)
On pelvic ultrasound: ≥ 20 follicles of 2-9 mm per ovary (threshold updated in 2023) or ovarian volume ≥ 10 mL.
Mandatory exclusion conditions
PCOS can only be diagnosed after excluding conditions that can mimic its symptoms:
- Non-classic congenital adrenal hyperplasia (17-OH-progesterone)
- Cushing's syndrome (urinary free cortisol, dexamethasone suppression test)
- Hyperprolactinaemia (prolactin, pituitary MRI if needed)
- Androgen-secreting tumours
- Thyroid dysfunction (TSH)
The 4 phenotypes defined by Rotterdam
Depending on which criteria are present, 4 phenotypes are identified, each with distinct clinical and metabolic profiles:
- Phenotype A (full classic): OA + HA + PCOM
- Phenotype B (classic without PCOM): OA + HA
- Phenotype C (ovulatory): HA + PCOM (regular cycles)
- Phenotype D (normo-androgenic): OA + PCOM (without hyperandrogenism)
Learn more: PCOS phenotypes A/B/C/D.
ESHRE 2023 update
The 2023 ESHRE guidelines maintained the Rotterdam criteria as the standard while updating the PCOM threshold (AFC ≥ 20 instead of ≥ 12 follicles per ovary). They also introduced AMH as a potential marker for the morphological criterion in settings with calibrated laboratories.
Key takeaways
- 2 of 3 criteria required for diagnosis
- Criterion 1: oligo-anovulation
- Criterion 2: hyperandrogenism (clinical or biochemical)
- Criterion 3: PCOM (≥ 20 follicles/ovary or volume ≥ 10 mL)
- After exclusion of differential diagnoses
- International standard — updated ESHRE 2023
Frequently asked questions
How many of the Rotterdam criteria are needed for a PCOS / PMOS diagnosis?▼
At least 2 of the 3 criteria must be present — oligo-anovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology (PCOM) on ultrasound — and only after other conditions with similar symptoms have been excluded. This "2 of 3" rule is what distinguishes the Rotterdam criteria (2003) from the stricter NIH 1990 definition, which required both irregular cycles and hyperandrogenism.
What are the 4 Rotterdam phenotypes (A, B, C, D)?▼
Because any 2 of the 3 criteria are enough, four combinations are possible. Phenotype A ("full") has all three: hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology. Phenotype B has hyperandrogenism plus ovulatory dysfunction, without polycystic morphology. Phenotype C ("ovulatory") has hyperandrogenism plus polycystic morphology with broadly regular cycles. Phenotype D ("non-hyperandrogenic") has ovulatory dysfunction plus polycystic morphology without signs of excess androgens. Phenotypes A and B carry the highest metabolic risk, which is why the phenotype influences monitoring and treatment priorities.
Are the Rotterdam criteria still used in 2026, now that PCOS is called PMOS?▼
Yes. The 2023 International Evidence-Based Guideline (Monash/ESHRE/ASRM) kept the Rotterdam criteria as the diagnostic standard, updating the ultrasound threshold to at least 20 follicles of 2–9 mm per ovary and allowing AMH as an alternative to ultrasound in adults. The May 2026 consensus that renamed PCOS to PMOS changed the name only — the "2 of 3" rule, the exclusion work-up and the four phenotypes are unchanged.
Can you meet the Rotterdam criteria with regular periods?▼
Yes. Phenotype C (the "ovulatory" phenotype) is defined by hyperandrogenism plus polycystic ovarian morphology while cycles remain regular. Because 2 of the 3 criteria are enough, ovulatory PCOS / PMOS is possible — which is one reason a diagnosis should never be ruled out on cycle regularity alone.