Polycystic ovary (PCOS) — Reference values: Follicle number per ovary (FNPO), Ovarian volume, Rotterdam — PCOS diagnosis (2 of 3).
| Measurement | Usual value | Note |
|---|---|---|
| Follicle number per ovary (FNPO) | ≥ 20 follicles 2–9 mm | PCOS US criterion (2018 update; previously ≥ 12)Source: Intl Guideline 2018/2023 (ESHRE/ASRM) |
| Ovarian volume | ≥ 10 mL | alternative criterion (no cyst/corpus luteum)Source: Rotterdam / Intl Guideline |
| Criterion | Definition |
|---|---|
| Oligo/anovulation | clinical |
| Hyperandrogenism | clinical or biochemical |
| Polycystic ovaries on US | FNPO ≥ 20 OR volume ≥ 10 mL |
Needs 2 of 3 + exclusion of other causes. Do not apply the US criterion within < 8 years post-menarche.
Source: Intl Evidence-based Guideline (ESHRE/ASRM)