Fact-sheet: Ovarian polycystic syndrome
  • Polycystic ovary syndrome
  • Polyendocrine metabolic ovarian syndrome


Updated on 08/25/2026 at 1:12 PM

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Definition

Polycystic Ovarian Metabolic Syndrome (PMOS), formerly known as Polycystic Ovary Syndrome (PCOS), is a complex multisystem disorder. It is an abnormality of folliculogenesis characterized by hyperandrogenic anovulation.

It is the most common cause of infertility and hyperandrogenism in women of reproductive age (5 to 10% prevalence).

Clinical features

Presentation is heterogeneous and is historically based on the classic Stein-Leventhal triad:

  • Cycle disorders: Oligomenorrhea or anovulation (cycles > 45 days).
  • Hirsutism: Assessed using the Ferriman-Gallwey score (> 6).
  • Obesity: Present in approximately 80% of cases in the US, less consistently elsewhere.
  • Associated signs: Severe acne, alopecia, acanthosis nigricans (dark skin patches), pelvic pain, and mood disorders (anxiety, depression).

Long term, it is a risk factor for cardiovascular disease and Endometrial cancer

Laboratory findings

  • Reversal of the LH/FSH ratio
  • Hyperandrogenism: Elevation of free testosterone, androstenedione, or dehydroepiandrosterone sulfate (DHEAS).
  • Anti-Müllerian Hormone (AMH): Generally elevated; it accurately reflects the follicular reserve seen on ultrasound and can now be used as a diagnostic marker.
  • Metabolism: Insulin resistance and hyperinsulinism, leading to decreased SHBG (carrier protein), which increases the free fraction of androgens.

Ultrasound

First-line examination.

Should be performed transvaginally (probe > 6 MHz) for optimal resolution, except in virginal patients.

Diagnostic criteria (2023 update)

For women more than 8 years post-menarche, the thresholds are:

  • Follicle number per ovary (FNPO): >= 20 (follicles measuring 2 to 9 mm) in at least one ovary. This is the most accurate criterion.
  • If image quality is insufficient for counting: Ovarian volume: >= 10 mL (in the absence of a corpus luteum or a dominant follicle > 10 mm).
  • Follicle number per section (FNPS): >= 10.

Other signs (non-pathognomonic):

  • Peripheral distribution: "String of pearls" appearance.
  • Stroma: Hypertrophied, hyperechoic, and centrally located.
  • Doppler: Stromal hypervascularization (increased peak systolic velocity, decreased pulsatility index), although these signs are highly subjective.

Crucial note: Ultrasound should not be used for diagnosis in adolescents (< 8 years post-menarche or < 20 years of age), as multifollicular ovaries are physiologic at this age.

CT

CT is not indicated for the diagnosis of PMOS itself.

Its usefulness lies solely in excluding adrenal masses (Cushing's syndrome, secreting tumors) in cases of severe hyperandrogenism.

MRI

MRI is not routinely performed. It is indicated in cases of severe obesity limiting ultrasound assessment or suspicion of a secreting tumor.

  • T1-weighted sequences: Follicles appear hypointense, stroma shows intermediate signal.
  • T2-weighted sequences: Excellent contrast resolution. Follicles show marked hyperintensity, central stroma shows hypointensity (fibrosis).
  • Gadolinium injection: Ring-like enhancement around the microfollicles, giving the ovary a "honeycomb" appearance.

Management

The diagnosis is based on the revised Rotterdam criteria (2023). At least two of the following criteria are required:

  • Ovulatory dysfunction (oligo-anovulation).
  • Hyperandrogenism (clinical or biochemical).
  • Polycystic ovarian morphology on imaging OR elevated AMH level.

--> If the first two criteria are present, ultrasound is therefore not necessary for the diagnosis.

In cases of hirsutism, a combined estrogen-progestin pill is recommended as first-line therapy. Its progestin component inhibits LH secretion and reduces ovarian androgen production. The estrogen component decreases circulating androgen levels. If the combined estrogen-progestin pill fails, treatment relies on an anti-androgen (cyproterone acetate) combined with a natural estrogen. Cyproterone acetate is effective within three months for acne and within six months for hirsutism, but requires monitoring due to an increased risk of meningioma.

Dydrogesterone is an option for endometrial protection.

Therapeutic options for hirsutism: spironolactone, laser.

Metabolic abnormalities, on the other hand, are treated with lifestyle and dietary measures as first-line therapy, followed by oral antidiabetic agents if needed.

Classification

The reference classification is that of the Rotterdam Consensus Conference (2003), updated by the 2018 and 2023 International Guidelines. The follicle count threshold increased from >=12 (2003 criteria) to >=20 (2023 criteria) owing to improved probe resolution.

Differential diagnosis

  • Congenital adrenal hyperplasia
  • Cushing syndrome
  • Androgen-secreting tumors: Often characterized by testosterone > 2 ng/mL, marked ovarian asymmetry, and absence of a typical polycystic appearance
  • Ovarian hyperthecosis: Extreme form with severe virilization, often spherical ovaries with predominant stroma