Rotterdam criteria

The Rotterdam criteria are the framework used to diagnose PMOS. A diagnosis requires at least two of the following three, once other conditions that can mimic it have been ruled out:

First, hyperandrogenism, either measured in the blood or seen in signs like hirsutism and acne. Second, ovulation problems, usually showing as infrequent or absent periods. Third, polycystic ovary morphology on ultrasound.

Because only two of three are required, PMOS can present in different combinations, which is part of why it looks so different from person to person. The 2023 International Guideline kept these criteria, and the 2026 rename to PMOS did not change them. For adolescents, the rules are stricter: both hyperandrogenism and ovulation problems are required, and the ultrasound is not used.