Rotterdam criteria (2003) require at least 2 of 3 features for PCOS diagnosis: oligo/anovulation, clinical/biochemical hyperandrogenism, and polycystic ovarian morphology (PCOM) on ultrasound. PCOM is defined on transvaginal ultrasound as:
- A ≥12 follicles measuring 2–9 mm in diameter in at least one ovary OR ovarian volume >10 mL
- B ≥12 follicles in both ovaries combined measuring 2–9 mm and ovarian volume >12 mL
- C ≥20 follicles measuring 2–9 mm in diameter in at least one ovary OR ovarian volume >10 mL ✓
- D Antral follicle count >20 per ovary on 3D ultrasound only
Correct answer: C. ≥20 follicles measuring 2–9 mm in diameter in at least one ovary OR ovarian volume >10 mL
Explanation
The original Rotterdam 2003 criteria defined PCOM as ≥12 follicles measuring 2–9 mm in at least one ovary or ovarian volume >10 mL. However, updated international guidelines (International PCOS Network 2018 and ESHRE/ASRM 2023) revised the threshold upward to ≥20 follicles per ovary (using modern high-resolution transvaginal ultrasound) or ovarian volume >10 mL, to account for improved ultrasound resolution. The current evidence-based threshold is ≥20 follicles per ovary. The original criterion of ≥12 may generate false positives with contemporary equipment.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
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Written and medically reviewed by the StethoPrep medical team.