In this article:
Can an Ultrasound Alone Diagnose PCOS?
No. Doctors use ultrasound as one of the three main parts of the Rotterdam criteria for diagnosing PCOS.
To be diagnosed with PCOS, you need at least two out of these three markers:
- Irregular or missing periods
- Signs of high male hormones (like extra hair growth or acne)
- Ovaries that look polycystic on the scan
What Do Polycystic Ovaries Look Like on an Ultrasound?
When the sonographer looks at your ovaries during the scan, these are the key things that suggest polycystic ovaries:
- A large number of small follicles, usually 20 or more tiny fluid-filled sacs (each 2 to 9 mm in size) in at least one ovary.
- The follicles are often arranged around the edge of the ovary, giving a “string of pearls” or “peripheral” look.
- One or both ovaries may be bigger than usual. An ovarian volume greater than 10 ml or 10 cm³ is considered enlarged.
- The central part of the ovary (the stroma) can look more echogenic (brighter) than normal.
What Is the Difference Between a Normal Ultrasound and a PCOS Ultrasound?
A routine “normal” pelvic ultrasound is usually done from the outside (transabdominal) by placing the probe on your lower tummy, often with a full urinary bladder. It is the same kind of scan you have in early pregnancy.
For PCOS, doctors almost always prefer a transvaginal (internal) ultrasound because the probe is much closer to the ovaries, giving sharper and more reliable pictures of the tiny follicles and ovarian size. The internal scan is a bit more private and can feel strange at first. But it is quick, safe, and gives the clearest view, especially if you carry a little extra weight around your tummy.
Can You Still Have PCOS If Your Ultrasound Looks Normal?
Yes, absolutely. Many people who meet the other two criteria (irregular periods and high androgens) can still have PCOS even when their ovaries look normal in size and follicle count on the scan.
On the flip side, a lot of people have polycystic-looking ovaries on ultrasound but no symptoms or hormonal problems at all. This is why the scan result is only one piece of the puzzle.
What To Expect During a PCOS Ultrasound
This is what usually happens during a transvaginal ultrasound, so you know exactly what to expect:
- You will lie down on the examination bed with your knees bent.
- A slim transvaginal probe is covered with a protective sheath and lubricant.
- The probe is gently inserted into the vagina. It usually feels like pressure, not pain.
- The sonographer slowly moves the probe to get clear images of your uterus and ovaries.
- You can ask them to pause or adjust at any point if you feel discomfort.
- The scan typically takes about 10 to 20 minutes.
When Is the Best Time in Your Cycle to Have the PCOS Ultrasound?
The scan can technically be done at any time, even during your period. However, many doctors prefer doing it between days 2 and 5 of your cycle (the early follicular phase).
At this time, the lining of the womb (endometrium) is thin, and there is usually no dominant follicle or corpus luteum (the temporary structure formed after ovulation), which could otherwise make the ovary appear slightly bigger on the scan.
What Do Your PCOS Ultrasound Results Mean?
If your ultrasound shows polycystic ovaries along with irregular periods and signs of high male hormones, your doctor can confirm PCOS and guide you on what to do next.
This may involve lifestyle changes, medication to help with ovulation, or treatment for symptoms like excess hair or acne. And if your scan looks completely normal but your symptoms and blood tests still point to PCOS, you’ll still get the same support and treatment because the diagnosis doesn’t depend on the ultrasound alone.
Having a clear picture of your ovaries helps you and your doctor understand exactly what is happening and choose the options that suit you best. An ultrasound is a simple, safe step that brings a lot of clarity when you are trying to make sense of PCOS symptoms.
You’re not alone in your journey when trying to conceive. Join our supportive community to connect with others, share experiences, and find encouragement every step of the way.
FAQs on Understanding What a PCOS Ultrasound Shows
- Can an ultrasound tell if my PCOS is mild or severe?
No. An ultrasound can only show the appearance of your ovaries. PCOS severity depends on symptoms, hormone levels, and metabolic health. - What happens if PCOS is left untreated?
Untreated PCOS can increase the risk of infertility, diabetes, high cholesterol, and high blood pressure.
