If you have been told you might have Polycystic Ovary Syndrome (PCOS), or you are trying to make sense of your own symptoms, this guide explains exactly how PCOS is diagnosed in Australia in 2026 — including the 2023 update to the diagnostic criteria, what blood tests are required, and what your doctor needs to rule out before confirming a PCOS diagnosis.
PCOS affects roughly 1 in 8 Australian women and is the most common endocrine disorder of reproductive age — yet up to 70% of cases remain undiagnosed, and many women receive a diagnosis only after years of symptoms. Knowing the current diagnostic criteria helps you ask the right questions of your GP and avoid both under-diagnosis (missing the condition) and over-diagnosis (being told you have PCOS when you do not).
The Australian standard: 2023 International Evidence-based Guideline
Since 2023, Australian doctors diagnose PCOS using the 2023 International Evidence-based Guideline for the Assessment and Management of PCOS — developed in Australia at Monash University by a 39-organisation international collaboration, endorsed by the Australian Government National Health and Medical Research Council (NHMRC), and used as the reference standard by the RACGP and major Australian fertility specialists.
The 2023 guideline replaces (but builds on) the 2003 Rotterdam consensus and the 2018 international guideline. The substantive 2023 changes:
- AMH (Anti-Müllerian Hormone) can now substitute for ultrasound in adults — a major shift that reduces the need for pelvic imaging in many patients
- Simplified diagnostic algorithm — clearer guidance that women with both irregular cycles AND hyperandrogenism do not need either ultrasound or AMH testing
- Stricter adolescent criteria — both irregular cycles AND hyperandrogenism are required in adolescents, with ultrasound and AMH explicitly NOT recommended
The three diagnostic criteria — quick reference
To diagnose PCOS in an adult woman, your doctor needs to confirm at least 2 of the following 3 criteria, AND exclude other conditions that can mimic PCOS:
| Criterion | What it means | How it is assessed |
|---|---|---|
| 1. Hyperandrogenism | Clinical (acne, hirsutism, alopecia) OR biochemical (raised androgens) signs of excess male hormones | Physical examination + blood tests (total testosterone, SHBG, free androgen index, DHEAS) |
| 2. Ovulatory dysfunction | Irregular or absent menstrual cycles indicating absent or infrequent ovulation | Menstrual history (cycles >35 days or <21 days, or <8 cycles per year) |
| 3. Polycystic ovaries | Multiple small follicles visible on ultrasound, OR elevated AMH (new in 2023) | Pelvic ultrasound (transvaginal preferred) OR AMH blood test |
Plus the essential fourth step: exclusion of other causes that can produce similar symptoms.
The simplified 2023 diagnostic algorithm
This is the single most useful clinical insight from the 2023 guideline:
- If you have BOTH irregular cycles AND signs of hyperandrogenism (clinical or biochemical) — you already meet 2 of 3 criteria. No ultrasound and no AMH test are needed for diagnosis. This applies to roughly 70% of cases.
- If you have only ONE of the above two (just irregular cycles, or just hyperandrogenism), your doctor needs to confirm the third criterion — either a pelvic ultrasound or an AMH blood test (not both).
- In all cases, your doctor must rule out other conditions that mimic PCOS (see "differential diagnosis" below).
This algorithm matters because many Australian women have historically been over-tested or under-tested for PCOS depending on which lab their GP routes to and which referral pathway they follow.
Criterion 1: Hyperandrogenism (clinical or biochemical)
Hyperandrogenism means excess androgen activity. It can be confirmed either by visible signs (clinical) or by blood test (biochemical) — either qualifies.
Clinical hyperandrogenism:
- Hirsutism — terminal (coarse) hair growth in a male pattern (chin, upper lip, chest, lower abdomen, inner thighs). Assessed clinically using the modified Ferriman–Gallwey score; a score of ≥4–6 (depending on ethnicity) is considered abnormal.
- Acne — moderate to severe acne, especially persisting into the 20s and 30s, or located along the jawline and chin
- Androgenic alopecia — male-pattern hair thinning at the crown and temples
Biochemical hyperandrogenism — measured on blood tests:
- Total testosterone elevated above the female reference range
- Free Androgen Index (FAI = total T ÷ SHBG × 100) elevated above ~5 — this is the most sensitive marker; FAI rises when SHBG falls (which is common in PCOS due to insulin resistance)
- DHEAS may be elevated, although a markedly raised DHEAS should prompt looking for adrenal causes
- Androstenedione — sometimes measured as a more sensitive marker than total testosterone alone
Blood tests for androgens should ideally be performed in the morning, in the early follicular phase of the cycle (days 2–5 of menstrual bleeding), and off all hormonal contraception for at least 3 months for accurate baseline values. Hormonal contraception suppresses androgens and SHBG patterns, masking biochemical hyperandrogenism.
Criterion 2: Ovulatory dysfunction
Irregular menstrual cycles are the most easily assessed PCOS criterion — no blood tests required for this one. The 2023 guideline defines ovulatory dysfunction as:
- Cycles >35 days or <21 days apart in an adult woman
- Fewer than 8 menstrual cycles per year
- Absence of menstruation for 90 days or more
- In adolescents: irregular cycles for more than 1 year post-menarche (more lenient because cycles can be irregular naturally in the first year or two after first period)
If cycles look regular but ovulation is uncertain, a day-21 progesterone (or day-7-before-expected-period progesterone, if cycles are irregular) confirms or rules out ovulation. A progesterone level >15 nmol/L is consistent with recent ovulation.
Criterion 3: Polycystic ovaries (ultrasound OR AMH)
This is the criterion that changed most in 2023. Either of the following now qualifies (you do not need both):
Pelvic ultrasound — the traditional approach:
- ≥20 follicles per ovary on transvaginal ultrasound (using an 8 MHz probe), OR
- Ovarian volume ≥10 mL in one ovary
- Note: the old threshold of "≥12 follicles" or "≥10 mL" used in the 2003 Rotterdam criteria has been updated
OR — AMH (Anti-Müllerian Hormone) blood test — new in 2023:
- AMH elevated above the laboratory cut-off (typically >~30 pmol/L in Australian labs, varies)
- AMH can be tested any day of the cycle, no fasting required
- AMH is suppressed by hormonal contraception — allow ≥3 months off for accurate baseline
- AMH alone cannot diagnose PCOS — it has to be paired with at least one other criterion
The 2023 guideline explicitly states that AMH should not replace ultrasound in adolescents because AMH levels are naturally elevated in adolescents and lack diagnostic specificity at that age.
For more on AMH testing in Australia (including which lab bulk-bills it), see our AMH test cost Australia guide.
Adolescent diagnosis: stricter criteria
The 2023 guideline tightened PCOS diagnosis in adolescents to avoid over-diagnosis (a real problem given naturally irregular cycles in the years immediately after menarche). In adolescents:
- BOTH hyperandrogenism AND ovulatory dysfunction are required — not just two of three
- Ultrasound is NOT recommended — pelvic ultrasound in adolescents has poor specificity and high false-positive rate
- AMH is NOT recommended — naturally elevated at this age
- If criteria are not fully met but suspicion is high, the term "at increased risk of future PCOS" is used, with re-assessment at age 18 or 8 years post-menarche
What must be excluded before diagnosing PCOS
PCOS is in many ways a diagnosis of exclusion — multiple other conditions can produce hyperandrogenism, irregular cycles or polycystic-looking ovaries. The 2023 guideline mandates exclusion of:
- Thyroid dysfunction — TSH and free T4. Hypothyroidism can cause irregular cycles and weight gain.
- Hyperprolactinaemia — prolactin. A prolactinoma can cause oligomenorrhoea and infertility.
- Non-classical congenital adrenal hyperplasia (NCCAH) — 17-hydroxyprogesterone, ideally measured in the early follicular phase. NCCAH is the most important PCOS mimicker — often missed.
- Cushing''s syndrome — if features suggest it (central obesity, striae, easy bruising, hypertension), 24-hour urinary free cortisol or dexamethasone suppression test.
- Androgen-secreting tumour — if testosterone is markedly elevated (>5 nmol/L in women) or onset of virilisation is rapid, urgent investigation with imaging.
- Premature ovarian insufficiency (POI) — FSH, LH, estradiol. POI presents with elevated FSH and low estradiol, opposite to PCOS.
- Pregnancy — beta-hCG. Obvious but essential before workup of amenorrhoea.
For the specific blood test panel your GP will order, see our PCOS blood test Australia guide. For the practical pathway through Medicare and GP referrals, see how to get tested for PCOS in Australia.
The four PCOS phenotypes (A, B, C, D)
Once PCOS is diagnosed, it is sub-classified into four phenotypes based on which combination of criteria are met. This matters because different phenotypes carry different cardiometabolic and fertility risks:
| Phenotype | Criteria met | Notes |
|---|---|---|
| A (Classic, full) | Hyperandrogenism + Ovulatory dysfunction + PCO morphology/AMH | Highest cardiometabolic risk, most insulin resistance |
| B (Classic, no PCO) | Hyperandrogenism + Ovulatory dysfunction | High cardiometabolic risk |
| C (Ovulatory) | Hyperandrogenism + PCO morphology/AMH (regular cycles) | Lower cardiometabolic risk; preserved fertility |
| D (Non-hyperandrogenic) | Ovulatory dysfunction + PCO morphology/AMH (no excess androgens) | Lowest metabolic risk; sometimes overlaps with hypothalamic dysfunction |
Phenotype influences treatment priorities — phenotypes A and B usually need closer cardiometabolic monitoring (HbA1c, lipid panel, blood pressure annually) than phenotype D.
Why an accurate PCOS diagnosis matters
PCOS is not just a fertility or cosmetic issue. Untreated or undiagnosed PCOS carries longer-term risks:
- Type 2 diabetes — 4-fold increased risk over the lifespan, often emerging in the 30s–40s
- Cardiovascular disease — particularly with phenotype A or B
- Endometrial cancer — chronic anovulation means unopposed oestrogen exposure of the endometrium; risk is reduced by inducing regular bleeding (e.g. cyclic progestogens or hormonal contraception)
- Sleep apnoea — disproportionately common in PCOS, often missed
- Mood disorders — depression and anxiety occur at 3× the population rate
- Subfertility — often manageable with weight optimisation, ovulation induction (letrozole first-line in Australia) or IVF
Getting the diagnosis right means these risks can be screened for and modified early.
Tracking PCOS hormones and metabolic markers over time
PCOS management is a long-term process — annual or biennial checks of HbA1c, lipid panel, blood pressure, BMI, and reassessment of androgens are recommended. Tracking these markers over time matters more than any single reading. BloodTrack reads any Australian pathology PDF (4Cyte, Laverty, ACL, SNP, Dorevitch, QML, DHM, WDP), maps results to AU reference ranges, and charts every marker over time — useful for PCOS where small changes year-on-year inform treatment. Upload your PCOS panel, no account needed for your first analysis.
Medical disclaimer: This article is for educational purposes only and is not medical advice. PCOS diagnosis and management is individual — always discuss your symptoms, results and treatment options with your GP or endocrinologist.