Fertility Chronicles is proud to present a special blog series, “From the Fertility Experts,” where leading fertility experts answer commonly asked questions for patients about their fertility health and treatment options.We hope this series can help patients navigate their personal fertility journeys.—Catherine T. Yang, Editor, Fertility Chronicles
Dr. David Barad, our guest blogger, explained the use of Day 3 FSH testing in his other blog "The ABCs of Day 3 FSH," and now tells us about antral follicle count, another ovarian reserve test.
In my other blog post, I wrote about follicle-stimulating hormone (FSH) tests and how they can help gauge the health of your ovaries and how you proceed in your fertility treatment. In this post, I will explain how detecting antral follicles can also help to tell whether your ovaries will make good eggs in the context of fertility treatment. They are not necessarily a measure of your natural fertility.
The baseline day of your menstrual cycle, typically referred to as Day 2 or Day 3, is a good day to take your FSH blood test or your antral follicle count, or both, depending on your doctor’s recommendation. The Day 3 FSH test is a blood test measuring the levels of that hormone at the beginning of your cycle (e.g. Day 2 or 3). The antral follicle count is an ultrasound test to detect how many of these small follicles are in your ovaries at this point in your cycle.
A follicle houses and nurtures an egg as it develops from an immature stage to maturity which occurs at ovulation, when the follicle "bursts" to release the egg. In a natural cycle, only one follicle typically matures to ovulation while the other follicles stop developing during the cycle. Antral follicles are follicles that have the potential to develop in the current cycle.
The more antral follicles you have, the more eggs you can produce in response to stimulation from hormonal drugs. The fewer you have, the fewer eggs you will produce. If you are starting treatment, you want to know how many antral follicles are present in your ovaries now, since these follicles have the potential to give you eggs in this cycle. If you are considering IVF treatment, the antral follicle count can give you and your doctor some idea about the number of eggs you can expect to yield.
Modern ultrasound machines are sensitive enough to see your small antral follicles. Thus, one way your doctor can tell how your ovaries are working is to count the number of antral follicles present at the beginning of your cycle. Antral follicle counts of greater than six to 10 are expected to give you normal response to hormonal medications.
A high number of antral follicles is often seen with lower Day 3 FSH levels, whereas a small number of antral follicles is often seen with higher Day 3 FSH levels. FSH is the hormone that tells your ovaries to make eggs. If your ovaries are not responsive, FSH will rise until there is a response. So, responsive ovaries that produce many antral follicles are likely to correspond with low Day 3 FSH. Less responsive ovaries that produce fewer antral follicles are likely to correspond with high Day 3 FSH. Such test results can help guide you and your doctor on the next steps in your treatment.
Stay tuned for my next blog post on anti-mullerian hormones (AMH) and how they can detect ovarian reserves.