PCOS glossary · updated 18 May 2026

Rotterdam Criteria (2003)

International standard for PCOS diagnosis

This definition is a plain-language explanation. A PCOS diagnosis is made by a clinician following a complete clinical and biochemical assessment.

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

Go further:

Phenotypes A/B/C/D·Differential diagnosis·Other criteria (NIH, AES)·All glossary terms