Guide to Antral Follicle Count

Navigating fertility can be a daunting challenge, especially when you are bombarded by all the medical jargon. There are always new tests that need to be learned, one of them being the Antral Follicle Count or AFC. 

The AFC test is one of the first tools used by fertility specialists to get a clearer picture of an individual’s fertility. The  AFC plays a significant role in shaping the fertility journey, especially when it comes to creating a personalized fertility treatment plan.

Key Takeaways

• Follicles develop in groups during the menstrual cycle, but ultimately only one reaches full maturity and releases an egg during each cycle.
• Antral follicles are small, fluid-filled sacs with eggs inside them that grow on the outside of ovaries, eventually rupturing and releasing an egg during ovulation.
• Age is a major determinant of how many follicles grow and become viable in each cycle, but certain medications can stimulate follicles and increase the number reaching maturity at once.

What are Antral follicles?

Antral follicles are small fluid-filled sacs in the ovaries, each with an immature egg called an oocyte that is expected to mature. In other words, follicles don’t become antral follicles until the very final stage of their development (when they have an antrum). The mature egg will be released during the menstrual cycle and wait to be fertilized and give a positive pregnancy. 

Antral follicles are formed from birth but their development happens throughout a woman’s lifetime. The antral follicles, that don’t mature are discarded. The number of antral follicles a woman produces in each cycle is directly proportional to her ovarian reserve. 

Antral follicles go through the following stages of development.

• The primordial follicle is the first stage of the follicles in a newborn.
• Primary follicles are stimulated primordial follicles that develop when the oocyte enlarges, and the follicular cells divide. They have two layers of follicular cells. 
• Secondary follicles also contain theca cells and begin to secrete hormones.
• Antral follicles or tertiary follicles, have fluid-filled sacs known as antra and they can be seen on an ultrasound scan.
• Graafian follicle is the last stage of development. It’s when the egg inside the follicle is mature enough to ovulate. During a natural menstrual cycle, only one or sometimes two will reach this stage.
• Corpus luteum. This isn’t a follicle and it develops from the open sac that released the egg.

The Antral Follicle Count

An antral follicle count (AFC) is an ovarian reserve test performed by a transvaginal ultrasound that views the ovaries. The test only measures follicles 2-9mm but the results can be inconclusive in the presence of conditions like endometriomas or ovarian cysts. 

The AFC focuses on the antral follicles, specifically primordial follicles. The number of antral follicles that mature differs among women similar to how the AFC is highly dependent on age. Studies comparing the anti-mullerian hormone and the antral follicle count have shown that the antral follicle count is a great fertility indicator for ovarian reserves. 

Benefits of the AFC

There are many reasons why fertility specialists perform the AFC.

• To check for ovarian reserve. The AFC test allows specialists to know the number of eggs in a woman’s ovaries. It works better when complemented with blood tests to check the levels of follicle stimulating hormone (FSH), oestradiol, anti-Müllerian hormone (AMH), and luteinizing hormone (LH). 
• It reveals potential fertility problems. The test can reveal if the antral follicle count is low, a sign of decreased ovarian function, which affects fertility. 
• To confirm if ovarian stimulation has worked. The antral follicle count can help predict a woman’s response to ovarian stimulation. This is because if the number of antral follicles is low, the response to IVF hormone treatment may also be low, meaning that the treatment may not work as expected. Knowing the AFC will help the doctor determine the right drug protocol. 

How To Test The Antral Follicle Count (AFC)

When you visit Ivy Fertility, a fertility specialist will assess your antral follicle count, by performing a transvaginal ultrasound. The ultrasound reveals your antral follicles; the more follicles you have, the higher your chances for a successful pregnancy. If you’re going through IVF, the AFC indicates how many mature follicles can be stimulated by the fertility medications.

The AFC test is usually done 3 to 5 days into the menstrual cycle and takes a few minutes. If the antral follicle count is between 10 and 20 follicles, the ovarian reserve is normal. On the other hand, if the number is less than 10, the ovarian reserve is considered to be low. 

Other tests done alongside the AFC to check fertility include.

• Blood tests. Blood tests offer insight into ovarian reserve and levels of hormones like anti-Mullerian hormone (AMH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH).
• Genetic screening. Genetic testing is done to check for any inheritable genetic conditions. 

What Is A Normal Antral Follicle Count?

The total AFC is the sum of the antral follicles in both ovaries. This count varies between ovaries, and there’s usually no cause for concern as long as the total count is within the normal range. 

What is considered a normal AFC varies between institutions and most people look at a range to determine how high or low the count may be. Fertility specialists look at the following parameters.

• Below 4: This is an extremely low count and may not respond to ovarian stimulation.
• 4-9: Women with such a count will likely need high doses to stimulate ovaries adequately. 
• 9-21: This is an Intermediate to normal count with low to great response to drug stimulation. Most women fall into this category. 
• 22-35: This is also a normal antral count and people with this count react well to ovarian stimulation. 
• Over 35: This is a very high count and women with such a count may have polycystic ovarian syndrome (PCOS). 

One study found that information from an AFC can provide valuable insight into possible fertility treatments. It also showed that individuals with moderate to high AFC numbers were more successful in their IVF cycles overall. 

Normal Antral Follicle Count By Age:

When it comes to reproductive health and fertility, age plays a key role. AFC reduces with age, which means that the older one grows the fewer the follicles they have and the lesser the chances of becoming pregnant.  

A study conducted on women aged 25-46 years found an average AFC decline of around 5 percent for individuals under the age of 37, with that decline increasing to almost 12 percent in the following years.

• 20-24 years: 12-30 follicles
• 25-34 years: 13-25 follicles
• 35-40 years: 10-15 follicles
• 41-45 years: 3-10 follicles
• 46+ years: 0-3 follicles

Though a low AFC indicates a low ovarian reserve, it doesn't mean there’s infertility. The converse can also be true- a high AFC doesn't translate to egg viability. Women with low AFC can conceive naturally or with the help of fertility treatments.

Bottom Line

Even though the AFC test is a great way to asses a woman’s fertility, each woman is different and several factors including genetics and lifestyle play a huge role in pregnancy success. Additionally, a low AFC does not necessarily mean a healthy pregnancy is impossible. Many women have conceived naturally despite tests indicating a declining AFC.