There is no single blood test or scan that diagnoses PCOS. Instead, providers use a well-established framework called the Rotterdam criteria: PCOS is diagnosed when you have at least two of three signs — irregular or absent ovulation, signs of excess androgens, and polycystic-appearing ovaries on ultrasound — after ruling out other conditions that can look similar.
The three criteria, in plain language
- Irregular or absent ovulation. Cycles longer than 35 days, fewer than eight periods a year, or months with no bleeding.
- Signs of high androgens. This can be clinical — acne, unwanted facial or body hair, scalp hair thinning — or laboratory, meaning high testosterone or DHEA-S on blood work.
- Polycystic-appearing ovaries on ultrasound. This means many small follicles visible on the ovaries — not painful cysts, despite the name.
You need two of the three. Many women are diagnosed without ever having an ultrasound.
Ruling out look-alikes
A few other conditions can mimic PCOS, so a good evaluation rules them out: thyroid disorders (a simple blood test), high prolactin, and certain adrenal conditions. This step matters — treating the wrong cause wastes time.
What an evaluation looks like by telehealth
Most of PCOS diagnosis is history, symptom review, and labs — all of which work well by video. We talk through your cycles and symptoms in detail, order the right blood work (drawn at a lab near you, timed to your cycle when it matters), and refer you for an ultrasound only if the picture needs it. If you've been dismissed before — told your labs are "normal" or your symptoms are "just stress" — bring that history. A second, careful evaluation with properly timed labs often finds what a rushed one missed. Then we review everything together and give you a straight answer.
Book through our secure booking portal to start your evaluation with Bertine JeanLaurent, MSN, APRN, FNP-BC.
Frequently Asked Questions
Do I need an ultrasound to be diagnosed?
Not always. If you already meet two criteria — for example, irregular ovulation plus signs of high androgens — an ultrasound adds nothing required. It is most useful when the picture is unclear.
What if my labs come back normal?
Normal labs do not rule out PCOS. Timing matters — hormones drawn on the wrong cycle day can mislead — and some women meet the clinical criteria regardless. A second look with properly timed labs often tells a different story.