Polycystic ovary syndrome (PCOS) is a common condition, which affects around 1 in 10 women. Pelvic ultrasound scans are one of the key methods for diagnosing PCOS, as they enable doctors to identify any fluid-filled sacs (follicles) on a patient's ovaries, which can affect how they work.

📌 Learn more about the types of ultrasound for medical diagnoses here

What is polycystic ovary syndrome (PCOS)?

PCOS is mainly characterised by polycystic ovaries, which, despite their name, contain many follicles, not cysts.

Follicles are small fluid-filled sacs up to 8mm in size, in which eggs would usually develop. However, when you have PCOS, these sacs often won't release eggs, meaning ovulation and regular menstruation may not take place. This can make it more difficult for people with PCOS to get pregnant, and irregular periods (or none at all) are common symptoms.

It is also common for people with PCOS to have higher levels of ‘male’ hormones, and this might cause excess hair growth (hirsutism) on the face and body. Weight gain, thinning hair on the head, and oily, acne-prone skin are also symptoms of PCOS.

What causes PCOS?

There is no definitive cause for PCOS, but there are a number of associated factors that are linked to PCOS. These include obesity and diabetes, as insulin resistance can be a result of these conditions. Insulin resistance can impair glucose tolerance, which can result in additional androgen (’male’ hormone) production.

How can ultrasounds diagnose PCOS?

As PCOS is a syndrome, it has many symptoms, which differ greatly between women. You don't need to have all of them to be diagnosed with PCOS. The presence of polycystic ovaries alone is not always enough evidence for diagnosis, so your doctor might ask you to have a blood test to check for hormone levels, diabetes or high cholesterol.

The gold standard ultrasound scanning technique for assessing PCOS is Transvaginal ultrasound (TVS). A TVS is a type of internal ultrasound scan, used to examine the female reproductive system. A lubricated ultrasound wand is inserted inside the vaginal canal, which is not painful, but can cause mild discomfort. This is usually due to the need for patients to have a full bladder for the process, to enable clearer images.

Ultrasound imaging of the ovaries from a TVS can help your doctor to count the number of follicles, and assess the size of the ovaries. Polycystic ovaries can be defined by either one or both ovaries being more than 10ml over the usual size, or if there are more than 20 follicles on either or both ovaries.

In some cases, a transvaginal ultrasound may not be suitable, for example if a patient is not sexually active, or declines to undergo the procedure. In this case, an ultrasound from outside the body (transabdominal scan) can be carried out, though the accuracy for counting follicles is reduced.

Is there a cure for PCOS?

While PCOS is not curable, it is treatable and can be managed. Depending on your age and mobility, there are several lifestyle factors that can greatly improve PCOS symptoms.

In overweight women, long-term complications as a result of PCOS can be reduced significantly by weight loss - even as little as losing 5% of their body weight. This is why regular exercise is recommended for PCOS sufferers, as it can help lower the risks of obesity and insulin resistance.
A balanced diet, which includes plenty of fruit and vegetables, whole foods, and lean meats and fish can also improve symptoms. A dietician can help you with specific dietary advice, and your GP can provide a referral if you require further support.
To treat irregular menstruation, your doctor may recommend combined contraceptive pills or intrauterine systems (IUS). If you take the combined pill, you can induce regular and predictable periods, and lower the long-term risks of endometrial (womb lining) cancer. An IUS can keep the womb lining thin and reduce this risk, but it often does not induce regular periods.
Most women with PCOS are able to get pregnant with treatment, for example a short course of fertility pills at the beginning of the menstrual cycle, for several cycles.

PCOS is a common and treatable condition, but it can be difficult to diagnose. An ultrasound scan is a key method for accurately assessing the health, size and condition of your ovaries. If you think you might have PCOS, or want to find out more, you can book a pelvic ultrasound to get the answers you’re looking for.

📌 Next Steps: