How to Test for PCOS: UK Diagnosis Guide

How to test for PCOS is a question many people face after noticing irregular periods, unwanted hair growth, or other hormonal symptoms. Polycystic ovary syndrome (PCOS) is one of the most common hormonal conditions affecting people with ovaries in the UK, yet it often goes undiagnosed for years. There is no single definitive test; instead, diagnosis involves a combination of clinical assessment, blood tests, and pelvic ultrasound, guided by the Rotterdam criteria. This article explains the full diagnostic process, what to expect from NHS testing, and what happens once a diagnosis is confirmed.

What is PCOS and how is it diagnosed in the UK?

PCOS is diagnosed in the UK using the Rotterdam criteria, requiring at least two of three features: irregular periods, signs of excess androgens, and polycystic-appearing ovaries on ultrasound. No single test is sufficient; other conditions must be excluded first.

Polycystic ovary syndrome (PCOS) is diagnosed in the UK using the Rotterdam criteria, which require at least two of three features: irregular or absent periods, clinical or biochemical signs of excess androgens (male hormones), and polycystic-appearing ovaries on ultrasound. PCOS is one of the most common hormonal conditions affecting people with ovaries; NHS and NICE sources estimate it affects around one in ten women of reproductive age, though many remain undiagnosed for years.^[3][4]

The condition involves a combination of hormonal imbalance, insulin resistance, and genetic predisposition. Because its symptoms overlap with other conditions, including thyroid disorders and hyperprolactinaemia, diagnosis requires a structured clinical assessment rather than a single test. Importantly, PCOS is a diagnosis of exclusion: other causes of the presenting features must be ruled out before the label is applied.

In the UK, diagnosis is typically initiated by a GP, who will take a detailed history covering menstrual patterns, symptoms such as acne, unwanted hair growth (hirsutism), scalp hair thinning, and weight changes. A family history of PCOS or type 2 diabetes is also relevant. NICE guidance (NICE CKS: Polycystic ovary syndrome) supports a stepwise approach, beginning with clinical assessment before moving to investigations, and emphasises that no single test is sufficient on its own to confirm or exclude PCOS.^[1]

In adolescents, the diagnostic approach differs. Current international guidance (2023 International Evidence-Based Guideline for the Assessment and Management of PCOS, Monash/ESHRE/ASRM) advises against relying on ultrasound within eight years of the first period, because polycystic-appearing ovaries can be a normal finding in younger people. In this age group, diagnosis should be based on persistent menstrual irregularity and clear clinical or biochemical evidence of hyperandrogenism, with ultrasound reserved for cases where the clinical picture is uncertain.

Which tests do doctors use to check for PCOS?

Doctors use clinical assessment, blood tests, and pelvic ultrasound to check for PCOS. A pregnancy test is an important early step, and red flags such as rapid virilisation require urgent specialist referral.

Doctors use a combination of clinical assessment, blood tests, and pelvic ultrasound to check for PCOS. The specific tests chosen will depend on your symptoms and medical history. There is no single definitive test, so the diagnostic process is designed to build a picture across multiple areas.

The clinical assessment comes first. Your GP will ask about:

• Menstrual cycle regularity: cycles longer than 35 days, fewer than eight cycles per year, or absent periods are significant

• Signs of hyperandrogenism: hirsutism (scored using the Ferriman-Gallwey scale), acne, and androgenic alopecia^[8][9]

• Weight and body mass index (BMI): excess weight can worsen insulin resistance and hormonal imbalance in PCOS

• Blood pressure and skin changes: acanthosis nigricans (darkened skin patches) may suggest insulin resistance

Pregnancy exclusion is an important early step. If you have irregular or absent periods, your GP will usually arrange a pregnancy test before proceeding with further investigations, as pregnancy is a common cause of these symptoms and must be ruled out first.

Red flags requiring prompt specialist review include rapid-onset or severe virilisation (for example, deepening voice, clitoromegaly, or rapidly progressive hirsutism), markedly raised testosterone levels, features suggesting Cushing's syndrome, or a palpable pelvic mass. These findings warrant same-week or urgent referral to an endocrinologist or gynaecologist rather than routine investigation in primary care.

If clinical features suggest PCOS, your GP will arrange blood tests and, where appropriate, refer you for a pelvic ultrasound. In adolescents, ultrasound is generally not recommended within eight years of the first period; greater weight is placed on hormonal and clinical evidence in this group.

A diagnosis of PCOS does not require all three Rotterdam criteria to be present simultaneously. Two out of three is sufficient, provided other conditions that mimic PCOS have been excluded.

What blood tests and scans will I need?

Blood tests typically include testosterone, SHBG, LH, FSH, prolactin, TSH, 17-hydroxyprogesterone, fasting glucose, HbA1c, and a lipid profile. Pelvic ultrasound assesses ovarian morphology but must be interpreted alongside clinical and hormonal findings.

The blood tests used to investigate PCOS typically include a hormone panel and metabolic markers, ordered to both support the diagnosis and rule out other conditions. Your GP may request some or all of the following:

Hormonal blood tests:

• LH (luteinising hormone) and FSH (follicle-stimulating hormone): an elevated LH to FSH ratio is sometimes seen in PCOS but is not specific or required for diagnosis

• Total and free testosterone: raised levels indicate hyperandrogenism

• Sex hormone-binding globulin (SHBG): often low in PCOS, which increases free androgen activity

• DHEA-S (dehydroepiandrosterone sulphate) and androstenedione: may be measured where adrenal hyperandrogenism is suspected

• Prolactin: to exclude hyperprolactinaemia, which can cause similar symptoms

• TSH (thyroid-stimulating hormone): to rule out thyroid dysfunction

• 17-hydroxyprogesterone: to exclude congenital adrenal hyperplasia; this sample is best taken in the morning during the follicular phase of the cycle for accurate interpretation

Metabolic tests:

• Fasting glucose and HbA1c: to assess for insulin resistance or type 2 diabetes

• Oral glucose tolerance test (OGTT): recommended by international PCOS guidelines, particularly if you have a BMI of 25 or above, a family history of type 2 diabetes, or other risk factors; the OGTT can detect impaired glucose tolerance that HbA1c or fasting glucose alone may miss^[2][11]

• Fasting lipid profile: PCOS is associated with an increased risk of dyslipidaemia

Pelvic ultrasound is used to assess ovarian morphology. Based on current international guidance (2023 International Evidence-Based Guideline for the Assessment and Management of PCOS), a polycystic-appearing ovary is defined as having 20 or more follicles measuring 2 to 9 mm in diameter, or an ovarian volume greater than 10 ml, in either ovary; however, these thresholds depend on the ultrasound equipment used and operator experience, and should not be applied in isolation. A transvaginal ultrasound provides the clearest images, though a transabdominal scan may be used if a transvaginal approach is not appropriate or acceptable. Polycystic-appearing ovaries on ultrasound alone do not confirm PCOS; the finding must be interpreted alongside clinical and hormonal results. In adolescents within eight years of their first period, ultrasound is generally not recommended as a diagnostic tool.

Can I get tested for PCOS through the NHS?

Yes, NHS PCOS testing begins with a GP appointment at no cost; your GP can arrange blood tests and refer you for ultrasound without a specialist referral. Private options are available for faster access, but results must be reviewed by a qualified clinician.

Yes, testing for PCOS is available through the NHS, and the process usually begins with a GP appointment. You do not need a specialist referral to start the investigation. Your GP can arrange the initial blood tests and refer you for a pelvic ultrasound if clinically indicated, all without charge at the point of care.

If your results are inconclusive, or if your symptoms are complex or severe, your GP may refer you to a gynaecologist or an endocrinologist for further assessment. Referral thresholds can vary between Integrated Care Boards (ICBs), which commission local NHS services, so waiting times and the specific pathway may differ depending on where you live.

For those who prefer not to wait for an NHS appointment, or who want a faster assessment, private GP services and online clinics can arrange blood tests and consultations. Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online consultations with prescriber review and pharmacist support, which may be relevant if you are also exploring treatment options following a diagnosis. Any private testing should be interpreted by a qualified clinician, and results should be shared with your NHS GP to ensure continuity of care.

Some people seek direct-access blood testing through private laboratories. While this can provide useful information, a standalone blood result without clinical context is not sufficient to diagnose PCOS, and a clinician review remains essential.

What happens after a PCOS diagnosis?

Management after a PCOS diagnosis is personalised and covers lifestyle changes, symptom-specific treatments such as the combined oral contraceptive pill or metformin, fertility support if needed, and long-term monitoring of cardiometabolic and endometrial health.

After a PCOS diagnosis, management is tailored to your individual symptoms, reproductive goals, and metabolic health, because PCOS affects people differently and there is no single treatment that addresses all aspects of the condition. NICE guidance (NICE CKS: Polycystic ovary syndrome) recommends a personalised approach covering lifestyle, symptom management, and long-term health monitoring.

Lifestyle measures are a cornerstone of management. Evidence cited in the 2023 International PCOS Guideline suggests that even modest weight loss of around 5 to 10% of body weight in those with a higher BMI can improve hormonal balance, menstrual regularity, and fertility.^[2] A balanced diet and regular physical activity are recommended for all people with PCOS, regardless of weight.

Symptom-specific treatments may include:

• Combined oral contraceptive pill: to regulate periods and reduce androgen-related symptoms such as acne and hirsutism

• Metformin: NICE CKS supports its use in PCOS for menstrual irregularity and metabolic risk, particularly in those with a higher BMI or evidence of insulin resistance. Its use in PCOS is off-label in the UK, meaning it is prescribed outside its licensed indication; this should be discussed with your prescriber, who will weigh the likely benefits against your individual circumstances

• Treatments for hirsutism: topical eflornithine cream is licensed for facial hirsutism. Anti-androgen medicines (such as spironolactone, finasteride, or cyproterone acetate) are sometimes used but carry a risk of harm to a developing foetus; effective contraception is essential throughout treatment and for a period after stopping. These medicines should only be used under specialist or GP supervision with appropriate safety monitoring, in line with NICE CKS guidance on hirsutism

• Fertility support: letrozole is commonly used as first-line treatment for ovulation induction in PCOS, though its use for this purpose is off-label in the UK.^[14][15] Clomifene is an alternative. Both should be prescribed and monitored by a clinician with appropriate expertise, in line with the NICE guideline on fertility problems (assessment and treatment). Referral for assisted conception may be appropriate in some cases

Endometrial protection is an important consideration if you have infrequent periods. Prolonged anovulation can lead to endometrial hyperplasia. If you are having fewer than four periods per year and are not using a combined oral contraceptive pill, your GP may recommend cyclical progestogen to induce regular withdrawal bleeds and protect the endometrial lining.

Long-term monitoring is important because PCOS is associated with increased cardiometabolic risk factors, including a higher likelihood of developing type 2 diabetes, dyslipidaemia, and hypertension. The evidence for increased cardiovascular event risk is less certain, and your GP will focus on monitoring and managing these underlying risk factors rather than treating a confirmed elevated event risk. PCOS is also associated with endometrial hyperplasia (from prolonged anovulation) and mental health difficulties including anxiety and depression. Periodic review of metabolic markers, blood pressure, and emotional wellbeing is recommended.

If you experience new or worsening symptoms between appointments, contact your GP in the first instance. For urgent concerns, NHS 111 can provide advice. Any suspected adverse effects from prescribed treatments should be reported via the MHRA Yellow Card scheme at https://yellowcard.mhra.gov.uk/.

Scientific References

1. Polycystic ovary syndrome – Diagnosis: Investigations.
2. Polyendocrine metabolic ovarian syndrome (PMOS) guideline document (GID-NG10436).
3. Polyendocrine metabolic ovarian syndrome (PMOS).
4. Recent advances in polyendocrine metabolic ovarian syndrome, formerly polycystic ovary syndrome, with emphasis on endocrine and metabolic dysfunction and cardiovascular risk.
5. International evidence-based recommendations for polycystic ovary syndrome in adolescents.
6. Update on diagnosis of polycystic ovary syndrome during adolescence.
7. The value of anti-Mullerian hormone for diagnosing polycystic ovary syndrome in adolescents: a case-control study based on an epidemiological survey.
8. Grading of Hirsutism in Females: A Pilot Study.
9. Use of community-based reference ranges to estimate the prevalence of polycystic ovary syndrome by the recognised diagnostic criteria, a cross-sectional study.
10. Ultrasonographic criteria in the diagnosis of polycystic ovary syndrome: a systematic review and diagnostic meta-analysis.
11. Comparison of diabetes mellitus and insulin resistance screening methods for women with polycystic ovary syndrome.
12. Medicines with teratogenic potential: what is effective contraception and how often is pregnancy testing needed.
13. Metformin hydrochloride – BNF.
14. Comparative Outcomes of Letrozole Versus Clomiphene Citrate for Ovulation Induction in Patients With PCOS: Systematic Review and Meta-Analysis.
15. Comparative study of two ovulation induction therapies and laparoscopic ovarian drilling on clinical outcomes in women with clomiphene citrate-resistant polycystic ovary syndrome.
16. Comparative Analysis of Progestin Intervention for Non-Atypical Endometrial Hyperplasia in Infertile Females with Anovulation: A Retrospective Study.
17. Cancer risk and PCOS.
18. PCOS and Obesity: Contraception Challenges.

Frequently Asked Questions