PMOS: The New Name for PCOS

Irregular cycles are defined by time since menarche. Cycles are normal in the first year. From one to three years post-menarche, irregular means shorter than 21 days or longer than 45. From three years post-menarche onward, shorter than 21 or longer than 35 days, or fewer than eight cycles a year.

Pitfall: patients on combined oral contraceptives have a pharmacologically imposed cycle. You cannot assess ovulatory function through it, and you cannot assess androgens through it either.

Clinical hyperandrogenism means hirsutism, acne, or androgenic alopecia. Hirsutism alone is predictive of biochemical hyperandrogenism in adults.

Biochemical: measure total and free testosterone, preferably by liquid chromatography tandem mass spectrometry. Where direct assays are unavailable, use calculated free testosterone or the free androgen index.

Pitfall: markedly elevated testosterone should redirect you toward an androgen-secreting tumor or nonclassic CAH, not toward this diagnosis.

In adults, irregular cycles plus hyperandrogenism satisfies the criteria. No imaging is required, and no imaging adds anything.

This is the single most under-applied point in the guideline. A large number of pelvic ultrasounds ordered for this workup change nothing about the diagnosis or the management.

This remains a diagnosis of exclusion. Before labeling, rule out thyroid dysfunction (TSH), hyperprolactinemia (prolactin), and nonclassic congenital adrenal hyperplasia (early-morning 17-hydroxyprogesterone).

Consider Cushing syndrome, acromegaly, primary ovarian insufficiency, and androgen-secreting tumors when the presentation is atypical, rapid in onset, or severe.

Why it matters: the label follows a patient for decades and now carries a new name. Getting it wrong means a lifetime of the wrong screening schedule.

If only one of the first two criteria is present, you need ovarian morphology to complete the picture.

Ultrasound threshold in adults is 20 or more follicles per ovary on transvaginal imaging, or ovarian volume of 10 mL or greater. The old threshold of 12 follicles reflected older equipment and generates false positives on modern probes.

AMH is an acceptable alternative to ultrasound for defining ovarian morphology in adults. It must not be used as a standalone diagnostic test, and it is not validated for this purpose in adolescents.

At diagnosis: weight, waist circumference, blood pressure, and a full lipid profile. Assess glycemic status with a 75 g oral glucose tolerance test where feasible, since fasting glucose and HbA1c both underperform in this population.

Reassess glycemic status every one to three years based on individual risk. Screen for obstructive sleep apnea, MASLD, depression, anxiety, and disordered eating.

Key point: cardiovascular and diabetes risk are elevated independent of BMI. A normal BMI does not exempt a patient from this screening.

Do not use ultrasound in adolescents. Multifollicular ovaries are normal in this age group.

Irregular menses, acne, and hirsutism all overlap with normal pubertal development, so both criteria must be clearly present. Where the picture is uncertain, the guideline permits designating a patient "at risk" and deferring the diagnosis, with reassessment at or before 8 years post-menarche.

Discuss the timing of assessment openly with the patient and family. Deferring is a legitimate clinical decision, not a failure to act, and treatment of individual symptoms can proceed in the meantime.