What Is an Antral Follicle Count (AFC) Scan?

An antral follicle count (AFC) scan is an internal ultrasound that counts the small follicles in your ovaries. Each follicle contains an immature egg, so your count gives an indication of your ovarian reserve: roughly, how many eggs you have left. AFC naturally falls with age, so your result is most useful when it’s compared with what’s expected for your age.

If you’re planning for the future, thinking about egg freezing, preparing for IVF or trying to understand your fertility, you may have been advised to have an AFC scan. This guide explains what the scan involves, when it’s done, what your result means and how it compares with an AMH blood test.

Quick facts

• An AFC scan is a transvaginal (internal) ultrasound that counts the small follicles, usually 2 to 10mm across, in both ovaries.
• The scan can be done at any point in your cycle, though it’s usually done early in your menstrual cycle, between days 2 and 7, when small follicles are easiest to count.
• The scan usually takes 10 to 20 minutes. Most people find it mildly uncomfortable rather than painful.
• A low AFC suggests a lower ovarian reserve for your age, but it doesn’t mean you can’t get pregnant naturally.
• A high AFC usually means a high ovarian reserve, but it can also be a sign of PMOS.
• AFC and AMH measure ovarian reserve in different ways. Together, they give the clearest picture.

What is an antral follicle count (AFC)?

An AFC ultrasound is a scan that counts your antral follicles. These are small, fluid-filled sacs in your ovaries, and each one contains an immature egg. Together, they reflect your ovarian reserve: roughly, how many eggs you have left.

Your antral follicle count is the total number of these follicles across both ovaries. It gives doctors a direct, visual indication of your ovarian reserve.

An AFC is usually done as part of a pelvic ultrasound scan. The same scan can also check your ovaries and womb for things that could affect your fertility or cause symptoms, such as cysts, fibroids or polyps.

AFC is usually part of a wider fertility assessment, alongside blood tests such as AMH and sometimes FSH. Together, these help build a fuller picture of your ovarian reserve and anything else that could affect your fertility.

What can’t an AFC scan tell you?

AFC is a useful test, but it has limits:

• It can’t measure egg quality. A high count doesn’t mean your eggs are chromosomally normal, and a low count doesn’t mean they aren’t. Egg quality is more closely linked to your age.
• It can’t predict natural conception. Some people with a low AFC conceive easily. Others with a normal count have difficulty because of other factors, such as blocked fallopian tubes, sperm problems or unexplained infertility.
• It can’t diagnose infertility on its own. It’s one part of a wider fertility assessment.

AFC doesn’t predict your natural fertility or your ability to get pregnant without medical support, but when it comes to assisted conception, it can help shape decisions around medication doses or eligibility for certain types of treatment (like NHS-funded IVF).

That’s why your doctor will interpret your AFC alongside your other results and your medical history.

Why have you been recommended for an antral follicle count (AFC) scan?

You might be advised to have an AFC scan if you:

• want to understand your ovarian reserve, for example to plan when to start a family
• are thinking about egg freezing
• are preparing for IVF, IUI or other fertility treatment. 
• have been trying to conceive for a year, or six months if you’re 36 or over
• have irregular periods or symptoms of PMOS
• have a family history of early menopause
• have had hormone results that need a closer look, such as an AMH or FSH result that doesn’t match your age or symptoms

Why do you need to do an AFC scan for IVF and egg freezing?

AFC is one of the best tools for predicting how your ovaries will respond to fertility medication. Along with AMH, it helps your clinic:

• estimate how many eggs might be collected in a cycle
• choose the right medication dose
• spot whether you’re at higher risk of ovarian hyperstimulation syndrome (OHSS), a condition where the ovaries overreact to fertility drugs.

That’s why AFC is a routine part of IVF and egg freezing planning. The HFEA has more information on how egg numbers and age affect your chances.

What AFC can’t do is predict whether treatment will work. Research shows AFC is much better at predicting how many eggs will be collected than whether you’ll get pregnant. Your age has a bigger effect on success, because egg quality is largely linked to age.

AFC can also affect access to NHS-funded IVF.

When is the best time to have an antral follicle count (AFC)  scan?

If you have regular periods, an AFC is usually done early in your cycle, between days 2 and 7. At this point, the small follicles are all a similar size and easiest to count. Later in your cycle, a dominant follicle, a cyst or the corpus luteum (a temporary structure left behind after ovulation) can make the smaller follicles harder to see.

You can still have an AFC at other points in your cycle, and it can still give useful information, but your result may be more difficualt to interpret. If your cycles are irregular, or you use hormonal contraception, the timing may be different. Read our guide to the best time to have an AFC scan.

How is an antral follicle count (AFC) ultrasound done?

An AFC scan is usually done transvaginally (internally), because this gives the clearest view of your ovaries. It’s only done with your consent. A transabdominal scan, over your tummy, may be used instead if you aren’t comfortable, however, it may affect the scan results as the ovaries are much harder to see on a transabdominal scan.

1. You’ll be asked to undress from the waist down and lie on a table with your knees bent and legs apart, as you would for cervical screening. A sheet will cover you.
2. The sonographer gently places a thin ultrasound probe into your vagina. The probe is covered with a protective sheath and lubricating gel.
3. They count and measure the small follicles in each ovary, then check your womb and ovaries for anything else.

The scan usually takes 10 to 20 minutes.

Does an AFC scan hurt?

Most people find it mildly uncomfortable rather than painful, a bit like having a smear test. If you feel uncomfortable at any point, tell the sonographer. They can pause or adjust what they’re doing. You can also ask for a chaperone. Let your sonographer know beforehand if you have pelvic pain, vaginismus or a history of trauma, or if you feel anxious about internal examinations.

Tips to prepare for your AFC scan

• Book it for the right time. If you have regular periods, aim for between days 2 and 7 of your cycle, counting the first day of your period as day 1.
• It’s fine to have it during your period. You’ll just be asked to remove a tampon or menstrual cup beforehand.
• You don’t need to fast 
• If you are unsure whether an empty bladder or full bladder is more appropriate for your scan, we recommend arriving with a full bladder and double-checking with the practitioner before you begin. 
• Tell the clinic about any contraception or medicines, as some can affect your result.
• Wear something comfortable. A top you can keep on, with a skirt or trousers that are easy to take off, can make you feel more at ease.

For more preparation tips, including what to wear and whether you’ll need a full bladder, read our guide to the best time to have an AFC scan.

What can affect your antral follicle count (AFC)?

Age. This is the biggest factor. You’re born with all the eggs you’ll ever have, and the number falls throughout your life. Estimates suggest you’re born with around 1 to 2 million eggs. That falls to a few hundred thousand by puberty, around 25,000 by your late 30s and around 1,000 by the average age of menopause.

Your AFC reflects this decline. It usually falls gradually, then more quickly from your mid-30s. But there’s a lot of variation between people. Some women in their late 30s have counts similar to women in their 20s, while others see an earlier decline. That’s why your own result tells you more than your age alone.

The timing of your scan. Early in your cycle, your ovaries contain a group of small follicles of similar size. As the cycle goes on, one follicle usually grows larger and becomes dominant, while the others stop growing. That’s why the number of visible follicles changes across your cycle, and why AFC is usually measured between days 2 and 7.

Natural variation. Your count can vary a little from one cycle to the next, even when the scan is done on the same cycle day. Small changes like this are normal and don’t usually change how a fertility specialist plans treatment.

The scan itself. The equipment used and the sonographer’s experience can make a small difference to the count.

Hormonal contraception can temporarily lower your AFC. One study found it was around 18% lower in pill users. The effect reverses once you stop. For the most accurate result, Hertility generally recommends waiting three full cycles after stopping hormonal contraception before your scan. Don’t stop contraception you need without speaking to a clinician first.

Other factors. Smoking, previous surgery on your ovaries, endometriosis (particularly endometriomas, which are cysts linked to endometriosis) and chemotherapy or radiotherapy can also lower your AFC.

What is a normal antral follicle count?

There’s no single normal AFC that applies to everyone. Your AFC naturally falls with age, so a count that’s typical at 40 might be lower than expected at 28. Results also vary between clinics, because sonographers may use slightly different methods and cut-offs.

The most useful question isn’t whether your number is good or bad, but how it compares with what’s expected for someone your age. Your sonographer or doctor will interpret your result in that context.

What does a low antral follicle count (AFC) mean?

A low AFC means fewer small follicles were seen on your scan than expected for your age, which suggests a lower ovarian reserve. It doesn’t mean you can’t get pregnant. It reflects how many eggs you have, not their quality, and many people with a low count conceive without treatment. Ovarian reserve tests are much better at predicting how your ovaries will respond to fertility treatment than whether you’ll conceive naturally.

What it can mean for fertility treatment. If you’re having IVF or egg freezing, a low AFC is linked with fewer eggs being collected in each cycle. Medical guidelines uses a low AFC as one sign that someone may respond less strongly to medication. Your specialist may:

• adjust your medication dose
• suggest a different treatment protocol
• talk to you about other options, such as donor eggs, depending on your age and goals

AFC and AMH are both better predictors of how you’ll respond to fertility medication than FSH.

When it might be worth checking for POI. If you’re under 40 and your periods are irregular or have stopped, your doctor may want to check for premature ovarian insufficiency (POI). A low AFC on its own doesn’t diagnose it.

Can you freeze your eggs with a low AFC?

Yes. A low AFC doesn’t rule out egg freezing, but it usually means fewer eggs will be collected in each cycle. Your doctor may suggest:

• Freezing sooner rather than later, because your AFC is likely to fall further with age.
• Adjusting your treatment, such as changing the medication dose or protocol to get the most eggs from each cycle.
• More than one cycle, collecting and freezing eggs over several cycles to store enough. This is sometimes called egg banking.
• Other options, such as donor eggs, depending on your situation and what matters to you.

A Fertility Advisor Call can help you weigh up whether egg freezing is right for you.

What does a high antral follicle count (AFC) mean?

A high AFC usually means you have a high ovarian reserve: more eggs than average for your age. That can be good news if you’re planning ahead or thinking about egg freezing, because more eggs are likely to be collected in each cycle. But a higher count isn’t automatically better.

PMOS. People with PMOS (polyendocrine metabolic ovarian syndrome, formerly known as PCOS) often have more small follicles in their ovaries. A high AFC, often alongside a high AMH, is one possible sign of PMOS. But it can’t diagnose PMOS on its own.

The 2023 international PMOS guideline defines polycystic ovaries on ultrasound in one of two ways:

• 20 or more follicles in either ovary, measured with a high-resolution scanner
• a larger-than-usual ovarian volume

Having polycystic ovaries is only one of three features used to diagnose PMOS. You’d need to have two of the three, after other causes have been ruled out:

• irregular periods
• signs of higher androgens, such as acne or excess hair growth, or raised androgens on a blood test
• polycystic ovaries on a scan, or a high AMH

Read more about PMOS.

A strong response to IVF medication. A high ovarian reserve can mean your ovaries respond very strongly to fertility drugs. That raises the risk of OHSS. If your AFC is high, your clinic will usually adjust your medication to lower this risk.

Egg quality. A high ovarian reserve doesn’t tell you anything about egg quality, and it doesn’t guarantee you’ll conceive easily. Your age is still the biggest factor in your fertility.

What’s the difference between AMH and AFC?

AMH and AFC both estimate your ovarian reserve, but in different ways. AFC is a scan that counts the small follicles in your ovaries. AMH is a blood test that measures a hormone those follicles produce. Neither is clearly more accurate than the other, and used together they give the clearest picture.

How they work. An AFC gives a direct, visual count. A sonographer looks at your ovaries on an ultrasound scan and counts the follicles they can see. An AMH test takes an indirect measurement: the more small follicles you have, the more AMH they release into your blood.

When and where you can test. An AFC scan needs to be done in person at a clinic, ideally early in your cycle. AMH changes much less across your cycle, so it can usually be tested on any day, at a clinic or at home with a Hertility’s Advanced Hormone and Fertility Test.

What else each one shows. An AFC scan is part of a pelvic ultrasound, so it can also pick up cysts, fibroids, polyps and signs of PMOS. An AMH test can be done alongside other hormones that affect your cycle and fertility, such as FSH, oestradiol and thyroid hormones.

At Hertility, you can have both. AMH is included in Hertility’s Advanced Hormone and Fertility Test. Our Pelvic Ultrasound Scan includes an AFC alongside a check of your womb, ovaries and womb lining. Our clinicians can interpret both results together.

What if your AMH and AFC don’t match?

Most of the time, the two results tell a similar story. But sometimes they don’t. For example, you might have a low AFC with a normal AMH, or a low AMH with a high AFC. This can happen because of:

• hormonal contraception
• a scan done later in your cycle
• differences between labs or between scans
• PMOS, where AMH can be particularly high
• natural differences between people

A mismatch doesn’t necessarily mean something is wrong. Some research suggests the AFC may be a useful guide to how your ovaries will respond to IVF when the two disagree. But there’s no single rule, so your doctor will look at both results alongside your age, cycle and health history.

Find out more about what your AMH level means, or where to get an AMH test in the UK.

Can you get an AFC scan on the NHS?

You can ask your GP, but whether you can have an AFC scan on the NHS depends on your local Integrated Care Board (ICB) and its referral criteria. Some areas include a pelvic ultrasound in initial fertility investigations. Others only offer AFC once you’ve been referred to a fertility specialist. It’s usually only available if you’ve been trying to conceive for a year, or six months if you’re 36 or over, or if you have a known fertility concern.

If you’d like a scan to plan ahead, or you’re not eligible on the NHS, you can book an AFC scan privately without a GP referral with Hertility.

Ready to understand your ovarian reserve with Hertility?

Hertility’s Pelvic Ultrasound Scan includes an antral follicle count and a full check of your ovaries and womb. Every scan is reviewed by a Hertility gynaecologist, who writes a report explaining what your results mean. Pair it with Hertility’s Advanced Hormone and Fertility Test for the clearest picture of your ovarian reserve, with no GP referral needed.

Not sure where to start? Take the Online Health Assessment and we’ll recommend the right next steps for you.

References

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2. van Disseldorp J, Lambalk CB, Kwee J, et al. Comparison of inter- and intra-cycle variability of anti-Müllerian hormone and antral follicle counts. Human Reproduction. 2010;25(1):221–227. https://doi.org/10.1093/humrep/dep366
3. Birch Petersen K, Hvidman HW, Forman JL, et al. Ovarian reserve assessment in users of oral contraception seeking fertility advice on their reproductive lifespan. Human Reproduction. 2015;30(10):2364–2375. https://doi.org/10.1093/humrep/dev197
4. Ferraretti AP, La Marca A, Fauser BCJM, et al. ESHRE consensus on the definition of “poor response” to ovarian stimulation for in vitro fertilization: the Bologna criteria. Human Reproduction. 2011;26(7):1616–1624. https://doi.org/10.1093/humrep/der092
5. Broer SL, Dólleman M, Opmeer BC, et al. AMH and AFC as predictors of excessive response in controlled ovarian hyperstimulation: a meta-analysis. Human Reproduction Update. 2011;17(1):46–54. https://doi.org/10.1093/humupd/dmq034
6. Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Human Reproduction. 2023;38(9):1655–1679. https://doi.org/10.1093/humrep/dead156
7. ESHRE Reproductive Endocrinology Guideline Group, Bosch E, Broer S, et al. ESHRE guideline: ovarian stimulation for IVF/ICSI. Human Reproduction Open. 2020;2020(2):hoaa009. https://doi.org/10.1093/hropen/hoaa009
8. Broer SL, van Disseldorp J, Broeze KA, et al. Added value of ovarian reserve testing on patient characteristics in the prediction of ovarian response and ongoing pregnancy: an individual patient data approach. Human Reproduction Update. 2013;19(1):26–36. https://doi.org/10.1093/humupd/dms041
9. Human Fertilisation and Embryology Authority (HFEA). Egg freezing. https://www.hfea.gov.uk/treatments/fertility-preservation/egg-freezing/