Published on:
March 6, 2026
If you have been exploring your fertility options or considering treatments such as IVF or egg freezing, you have likely encountered the term Antral Follicle Count (AFC) scan. This quick, non-invasive ultrasound test is one of the most informative tools available for understanding your ovarian reserve — and, by extension, your reproductive potential. Whether you are planning for the future or actively trying to conceive, understanding what an AFC scan measures and what the results mean can help you make more informed decisions about your fertility journey.
An Antral Follicle Count scan is a transvaginal ultrasound used to count the small, fluid-filled sacs — known as antral follicles — visible in both ovaries at any given time. Each antral follicle contains an immature egg (oocyte) with the potential to mature and be released during ovulation. By counting these follicles, a fertility specialist or sonographer can gain a meaningful estimate of your remaining egg supply, which is referred to as your ovarian reserve.
The scan typically focuses on follicles measuring between 2 and 10 millimetres in diameter, as these are the ones most likely to respond to hormonal stimulation and mature into viable eggs. Follicles outside this size range are generally not counted, as they are either too immature or already past the stage at which they would be useful for fertility treatment. The procedure itself is straightforward: a small ultrasound probe is gently inserted into the vagina, and the sonographer captures detailed images of both ovaries, counting the antral follicles visible in each.
For an accurate result, the AFC scan is ideally performed between days 2 and 5 of your menstrual cycle — often referred to as a "day 3" scan — when follicle activity is at its most consistent and comparable baseline. You can learn more about what to expect from a gynaecology ultrasound at Spital Clinic London.
Women are born with a finite number of eggs — typically around one to two million — and this supply decreases naturally with age. By the time a woman reaches puberty, she may have around 300,000 to 500,000 eggs remaining. This number continues to decline throughout the reproductive years, accelerating particularly after the age of 35. Unlike sperm, eggs cannot be replenished, which is why assessing ovarian reserve is such a central part of fertility evaluation.
A diminished ovarian reserve does not necessarily mean a woman cannot conceive naturally, but it can indicate that the window for conception may be narrowing. For those pursuing fertility treatments, ovarian reserve is a critical factor in predicting how the ovaries will respond to stimulation medications — a process that is essential in both IVF and egg freezing cycles. Women with a higher AFC are likely to produce more eggs in response to stimulation, which generally improves the chances of a successful outcome.
It is equally important to note that ovarian reserve is not a measure of egg quality. A woman may have a low AFC but still have good-quality eggs, or she may have a high count but eggs of variable quality. AFC is best understood as one piece of a broader fertility picture, and it should always be interpreted alongside other assessments. If you are concerned about fertility or have been experiencing difficulties conceiving, our infertility support page provides further information on next steps and available services.
AFC results are generally categorised into ranges that help clinicians and patients understand where an individual sits relative to what is expected for their age. While exact thresholds can vary slightly between clinics and laboratories, a commonly used framework is as follows:
It is worth noting that these ranges are not absolute. What constitutes a "normal" AFC varies with age. A count of 10 might be perfectly reassuring for a 38-year-old but lower than expected for someone in their late twenties. Your clinician will always contextualise your results within the full picture of your age, medical history, and other fertility markers.
The AFC scan is rarely used in isolation. It is considered most informative when combined with blood tests that measure key reproductive hormones. The most commonly used alongside AFC are:
Together, the AFC scan and hormone blood tests are widely regarded as the gold standard for fertility assessment. This combined approach gives a more complete and reliable picture than either test alone. At Spital Clinic London, a gynaecological scan and consultation can incorporate both the AFC ultrasound and hormone testing as part of a thorough evaluation.
An Antral Follicle Count scan may be recommended for a wide range of individuals and circumstances. You might consider requesting one if you:
The scan is also valuable for those already engaged in fertility treatment, as baseline AFC results help clinicians tailor stimulation protocols to minimise risk and maximise the chances of retrieving an optimal number of eggs. Conditions such as perimenopause can also influence ovarian reserve, and an AFC scan may be part of assessing hormonal and reproductive changes during this transitional phase.
The AFC scan is typically performed as a transvaginal ultrasound, which provides the clearest and most accurate images of the ovaries. A slender, specially designed probe is gently inserted into the vagina, emitting high-frequency sound waves that create detailed images of the ovaries on a monitor. Most women find the procedure comfortable; any mild pressure usually subsides immediately after the probe is removed. The entire process usually takes no longer than 10 to 15 minutes.
You do not need to do any special preparation beyond ensuring the scan is booked at the right point in your menstrual cycle. Wearing comfortable, loose clothing and emptying your bladder beforehand may add to your comfort during the appointment.
After the scan, your clinician will discuss the findings with you, ideally in conjunction with any blood test results. They will explain what the follicle count means for your situation, outline any recommended next steps, and answer any questions you may have. If results indicate a lower-than-expected reserve, you should not be alarmed — there are still many pathways to parenthood, and your team will help you explore all appropriate options with clarity and compassion.
While the AFC scan is a powerful tool, it is important to understand its limitations. Firstly, the count can vary slightly between cycles and even between different sonographers, which is why it should always be interpreted as an estimate rather than an exact figure. Secondly, as mentioned earlier, AFC reflects quantity rather than quality — a high count does not guarantee that all, or even most, of those follicles contain chromosomally normal eggs.
Additionally, the AFC scan cannot predict whether a woman will conceive naturally. Many women with a low AFC conceive without difficulty, whilst others with a seemingly healthy reserve may face other barriers to conception. The scan also does not assess the health of the uterus, fallopian tubes, or any anatomical factors that may affect fertility — these require separate investigations.
Finally, certain conditions such as polycystic ovary syndrome (PCOS) can produce a very high AFC (often more than 20 follicles per ovary), which in this context does not necessarily reflect an unusually high egg supply but rather a hormonal imbalance affecting follicle development. Your clinician will factor in your full medical history when interpreting results.
Most women find the transvaginal AFC scan to be comfortable, with only mild pressure felt during the procedure. It is generally well tolerated and completed within 10 to 15 minutes. If you have any concerns about discomfort, do discuss them with your clinician beforehand so that appropriate measures can be taken.
For the most accurate and clinically meaningful results, the AFC scan is best performed between days 2 and 5 of your menstrual cycle. This is when the ovaries are at a baseline state and the antral follicles are most reliably counted. Scanning at other points in the cycle may still provide useful information but can be less consistent.
AFC and AMH are closely correlated — both measure aspects of ovarian reserve. AMH is produced by the granulosa cells of antral follicles, so a higher follicle count generally corresponds with higher AMH levels. However, they measure slightly different things and can occasionally diverge. Using both together provides a more complete picture of your ovarian reserve than either test alone.
Not necessarily. A low AFC indicates a reduced ovarian reserve, which may affect your response to fertility medications, but many women with a low count conceive naturally or with assistance. It is one factor among many, and a fertility specialist will assess your full clinical picture before drawing any conclusions about your prospects for conception.
Certain lifestyle factors, including smoking, can accelerate the decline of ovarian reserve. Some evidence also suggests that maintaining a healthy body weight and managing stress may support overall reproductive health. However, once follicles are lost, they cannot be recovered — AFC reflects a natural biological process that cannot be significantly reversed through lifestyle alone. If you are concerned, speaking with a women's health specialist is the best first step.
The information provided in this article is for educational purposes only and is based on NHS recommendations. It is not a substitute for professional medical advice. Always consult your doctor or a qualified healthcare provider for advice on medical conditions or treatments.
Our medical centre is at 36 Spital Square, E1 6DY, City of London.
