Guide to Antral Follicle Count

When you're going through infertility, there are a lot of tests and medical terms you will have to learn. One of these is the Antral Follicle Count (AFC). The AFC is based on the antral follicles, which are tiny fluid-filled sacs in the ovaries with immature eggs. The AFC plays a significant role in shaping the fertility journey since it’s one of the first tools used to get a clearer picture of a woman’s fertility.

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 of them has an immature egg called an oocyte. Follicles don’t become antral follicles until they reach the last stage of development when they develop an antrum. When the egg matures, it’s released during ovulation to await fertilization. Any antral follicles that don’t mature are discarded.

Antral follicles are formed from birth but their development happens throughout a woman’s lifetime. The number of antral follicles a woman produces in each cycle is directly proportional to her ovarian reserve. 

The Antral Follicle Count

An antral follicle count (AFC) is an ovarian reserve test used by fertility specialists to check how many eggs you have left and how viable they are. The test is done by a transvaginal ultrasound to view the ovaries and measures follicles 2-9mm. In some cases, the results can be inconclusive in the presence of conditions like endometriomas or ovarian cysts. 

The main focus of the AFC is the primordial follicles. These are follicles that contain undeveloped eggs and are the foundation of a female's reproductive system. The number of antral follicles that mature differs among women but can be greatly impacted by 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

Testing the AFC has several advantages. 

• One of the ways to know whether ovarian simulation has worked is by doing the AFC test. The test can also help predict a woman’s response to ovarian stimulation. This is because a low AFC result shows that response to IVF treatments may also be low. This means that the treatment may not work as expected. Knowing the AFC will help the doctor determine the right drug protocol. 
• The AFC helps to diagnose potential fertility problems, especially if the antral follicle count is low. A low AFC is an indicator of decreased ovarian function, which negatively affects fertility. 
• It helps to confirm a woman’s ovarian reserve or the number of eggs in a woman’s ovaries. The test is even more accurate when it’s used together with a blood test. The blood test checks the levels of follicle stimulating hormone (FSH), oestradiol, anti-Müllerian hormone (AMH), and luteinizing hormone (LH). 
• It helps create a treatment plan. 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. 
  

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 only 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 and this will vary between ovaries. However, you shouldn't be concerned if the numbers vary as long as the total count is within the normal range. 

• Below 4: This is an extremely low AFC and may not respond to ovarian stimulation.
• 4-9: This is also a low count and may require high doses of hormonal treatments when stimulating the ovaries. 
• 9-21: This is the most common AFC. It’s an intermediate to normal count and response to ovarian stimulation may differ among women. With low to great response to drug stimulation. 
• 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). 
  

Normal Antral Follicle Count By Age:

Age always plays a key role in reproductive health and fertility. As one ages, the AFC also reduces. This is one of the main reasons women 35 and above may require fertility treatments to get 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
  

Bottom Line

The AFC is a great tool in fertility diagnosis and treatment. Even though a low AFC indicates a low ovarian reserve, it doesn't mean one is infertile. And the converse can also be true. A high AFC doesn't translate to fertility. It could be a sign of an underlying condition like polycystic ovarian syndrome (PCOS). Nevertheless, a low AFC isn’t the end of the world. Women with a low AFC can conceive naturally or with the help of fertility treatments. Your fertility doctor will be able to curate a treatment plan for you based on the test results.