diagnosis
How Is PCOS Diagnosed? Tests, Ultrasounds, and What to Expect
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lina is a texting companion who remembers your cycle, your symptoms, and your questions between appointments. this article is a starting point, she's the ongoing part.
try lina freeThere's no single blood test, scan, or number that diagnoses PCOS on its own, which surprises a lot of people and is part of why diagnosis takes so long. It's a pattern based diagnosis, built from your history, bloodwork, and sometimes an ultrasound, put together.
Quick answer: most doctors use the Rotterdam criteria, which requires two out of three things: irregular or absent ovulation, clinical or lab signs of high androgens, and polycystic looking ovaries on ultrasound. You need two of the three, not all three, and other conditions have to be ruled out first.
The Rotterdam criteria, explained simply
This is the most widely used diagnostic framework. You need at least two of the following three:
- Irregular or absent ovulation, usually shown through irregular, infrequent, or missing periods
- Clinical or biochemical signs of high androgens, visible symptoms like excess hair growth or acne, or elevated androgen levels on a blood test
- Polycystic ovaries on ultrasound, meaning a higher than typical number of small follicles
This is why two people can both have PCOS and look completely different. One might have irregular periods and high androgens but a normal looking ultrasound. Another might have regular periods, elevated androgens, and polycystic ovaries. Both meet the criteria.
What the bloodwork actually checks
- Testosterone and other androgens, to check for hormonal elevation
- LH and FSH, hormones involved in ovulation, sometimes elevated or imbalanced in PCOS
- Fasting insulin and glucose, or an oral glucose tolerance test, to check for insulin resistance
- Thyroid function (TSH) and prolactin, to rule out other conditions that mimic PCOS symptoms
- Sometimes AMH (anti-Müllerian hormone), which tends to run higher in PCOS and can support the picture, though it's not part of the official criteria
What the ultrasound actually shows
A pelvic ultrasound, sometimes transvaginal for a clearer image, looks at the size of your ovaries and counts the small follicles present. Polycystic ovaries typically show 12 or more small follicles per ovary, or increased ovarian volume. Despite the name, these aren't cysts in the way most people picture them, they're immature follicles that didn't fully develop and release an egg that cycle. A normal looking ultrasound doesn't rule PCOS out if the other two criteria are met.
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walk into your appointment with the pattern already mapped
One of the most useful things you can bring to a diagnostic appointment is a clear history: how irregular your cycles actually are, what symptoms showed up and when. Lina keeps that record for you automatically, just by texting her along the way.
start texting linaConditions that get ruled out first
Before landing on a PCOS diagnosis, doctors typically rule out thyroid disorders, high prolactin, and a rarer condition called congenital adrenal hyperplasia, since all of these can cause similar symptoms. This is part of why the process involves bloodwork beyond just androgens, it's not just confirming PCOS, it's excluding everything else first.
Can I be diagnosed with PCOS without an ultrasound?
Yes. If you have both irregular ovulation and signs of high androgens, that already meets two of the three Rotterdam criteria, and a diagnosis can be made without imaging, particularly in teenagers where ultrasound findings are less reliable.
What doctor should I see for a PCOS diagnosis?
A gynecologist or an endocrinologist are the most common starting points. Many people start with a primary care doctor, who can run initial bloodwork and refer out if needed.
Can blood tests alone confirm PCOS?
Blood tests can show elevated androgens and rule out other conditions, but they're one piece of the criteria, not the whole diagnosis. You still need to consider ovulation patterns and, often, imaging.
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Lina helps you track your cycle, symptoms, and questions so you show up prepared instead of trying to remember three months of history on the spot. Free for 3 days, then $12.99 a month.
start texting linaThis article is general information, not medical advice. Lina isn't a replacement for a doctor, but she's a good place to think things through between appointments.