How to know if you have PCOS is a question I hear weekly, often from women who've spent months reading symptom checklists online and feeling more confused, not less. The honest answer is that PCOS is a clinical pattern, not a single test, and the path to a confident diagnosis is shorter than most readers expect once you know what to track.
If you're here because you suspect something is off with your cycle, your skin, or your fertility, this guide walks you through what to log at home, what your clinician will look for, and which conditions need to be ruled out before a PCOS label sticks. The same diagnostic groundwork also clarifies your conception path, which is why I usually link this post to can you get pregnant with PCOS early in the conversation.
What PCOS Looks Like Day to Day
A PCOS symptoms checklist is the easiest starting point because most of these signs are things you can already see, count, or track in a notes app. The most common patterns I see in clinic are irregular or absent periods, acne that persists or returns after adolescence, hirsutism (extra dark hair on the chin, upper lip, lower abdomen, or chest), scalp hair thinning, weight gain that settles around the middle, and difficulty conceiving despite well-timed intercourse.
Patients who come to me with "what are the early signs of PCOS" usually describe one or two of these symptoms, not all of them. PCOS is a spectrum, and a partial picture still deserves investigation.
Bring this PCOS symptoms checklist to your GP appointment: dates of your last 3 to 6 periods, cycle length range, skin changes (acne, oily skin), hair changes (excess body hair, scalp thinning), any unexplained weight pattern, and how long you've been trying to conceive if relevant. A clinician can move faster when you arrive with data.
For a fuller picture of how these signs map to fertility, the NHS PCOS diagnostic overview is a reliable plain-English starting point.
The Rotterdam Criteria, Explained
The Rotterdam criteria PCOS framework is the international standard. A diagnosis requires 2 of 3 features: (1) irregular or absent ovulation, (2) clinical or biochemical hyperandrogenism, and (3) polycystic ovarian morphology on ultrasound. [src]
In plain English: you need any two of these three. Irregular periods plus excess hair growth is enough. Polycystic-appearing ovaries on a scan alone is not. This last point catches many readers out, because a single ultrasound showing multiple small follicles is common in younger women and doesn't, on its own, mean PCOS.
The 2023 International Evidence-Based PCOS Guideline kept Rotterdam but tightened how the ultrasound criterion is applied and clarified the role of anti-Müllerian hormone in adults. If you're unsure how PCOS is being reframed metabolically, the difference between PMOS and PCOS is worth a read.
What Blood Tests Confirm PCOS?
There isn't one PCOS blood test, but there's a standard panel that confirms the pattern and rules out the conditions that mimic it. The bloods I typically request are total and free testosterone, sex hormone-binding globulin (SHBG, a transport protein that affects how much androgen is biologically active), free androgen index, LH and FSH, TSH (thyroid), prolactin, 17-hydroxyprogesterone, fasting glucose plus HbA1c, and a lipid profile.
Cycle timing matters. If you're still cycling, day 2 to day 5 of the period gives the cleanest hormone snapshot. If your periods have stopped, any day is acceptable. Insulin resistance often sits underneath PCOS, which is why I link PCOS, insulin resistance and fertility when discussing the metabolic side with patients.
Anti-Müllerian hormone (AMH, a blood marker of egg reserve) is often raised in PCOS, but it isn't on its own diagnostic. It supports a clinical picture; it doesn't make a diagnosis. Don't let a high AMH alone scare you into a label.
Conditions That Mimic PCOS (and Must Be Ruled Out)
Before any clinician confirms PCOS, five conditions need to be excluded because they can produce overlapping signs: thyroid dysfunction (hypo- or hyperthyroidism), hyperprolactinaemia (raised prolactin, often from a small pituitary adenoma), non-classical congenital adrenal hyperplasia (CAH, where 17-hydroxyprogesterone is elevated), Cushing's syndrome, and androgen-secreting tumours of the ovary or adrenal gland. [src]
This is why a symptoms checklist alone cannot diagnose. The AAFP and the 2023 international guideline both list these mimics, and missing one means a wrong treatment plan for years.
"Which doctor diagnoses PCOS" depends on where you live. In the UK, your GP is the first stop and will order the baseline bloods and arrange ultrasound or specialist referral. In the US, an OB-GYN or primary care provider typically initiates the workup, with referral to endocrinology or a reproductive endocrinologist (REI) depending on insurance and whether fertility is the dominant concern. If your symptoms started young and are mild, lean PCOS symptoms may be the phenotype to explore.
Ready for a personalised fertility plan?
Book a one-to-one consultation. We'll review your history and map the next concrete step.
NHS vs US Pathway to a PCOS Diagnosis
UK / NHS pathway: Book a GP appointment with your 3-cycle symptom log. The GP arranges baseline bloods (testosterone, SHBG, LH/FSH, TSH, prolactin, fasting glucose, lipids) and refers for pelvic ultrasound if indicated. Complex cases (suspected CAH, fertility concerns) are referred to gynaecology, endocrinology, or a fertility clinic. NICE recognises PCOS workup as part of standard subfertility assessment.
US pathway: OB-GYN or primary care provider runs the same baseline panel. Referral to endocrinology is common for metabolic complexity, and to an REI if fertility is the primary driver. Insurance coverage varies state-by-state for hormone panels and pelvic ultrasound; check whether your plan classifies them as preventive or diagnostic before booking.
What This Means for You
Track three cycles in a simple notes app, log skin and hair changes alongside, then book a GP or OB-GYN appointment with that data and ask for the Rotterdam workup specifically. Knowing how to know if you have PCOS is the first step toward a fertility plan that actually fits your body, not someone else's checklist.
If you'd like a second clinical opinion on your bloods or symptom pattern before committing to a treatment plan, an online consultation can save weeks of guesswork.
Ready for a personalised fertility plan?
Book a one-to-one consultation. We'll review your history and map the next concrete step.
What are the early warning signs of PCOS?+
The earliest signs are typically cycle irregularity (periods more than 35 days apart or fewer than 8 per year), new or persistent acne after adolescence, increased hair growth on the face or abdomen, and unexplained weight changes. Many women notice 1 to 2 of these years before a formal diagnosis.
Can I have PCOS with regular periods?+
Yes. The "ovulatory PCOS" phenotype involves hyperandrogenism (clinical or biochemical) and polycystic ovarian morphology with regular cycles. It meets 2 of the 3 Rotterdam criteria and is often missed because periods seem normal.
Does an ultrasound alone diagnose PCOS?+
No. Polycystic-appearing ovaries on a scan are one of the 3 Rotterdam features. You need at least 2 of the 3 (irregular ovulation, hyperandrogenism, polycystic morphology), and mimic conditions must be ruled out first.
Do I need AMH testing for PCOS?+
AMH is often raised in PCOS and supports the clinical picture, but it isn't on its own diagnostic. The 2023 international guideline allows AMH as a supportive marker in adults when ultrasound isn't available, not as a stand-alone test.
Which doctor should I see first for PCOS?+
In the UK, your GP. In the US, your OB-GYN or primary care provider. Both can order the baseline bloods and refer to endocrinology or a reproductive endocrinologist if needed.
Can teenagers be diagnosed with PCOS?+
Adolescent diagnosis is more cautious because irregular cycles and acne are common in the first 2 to 3 years after menarche. Most guidelines recommend waiting until at least 2 years post-menarche before formal diagnosis, with interim "at risk" monitoring.
References
Citations referenced inline above link to their primary sources (NHS, NICE, CDC, ACOG, ASRM, peer-reviewed journals).
