IVF and Antral Follicle Count
This information is provided for patients interested in their prognosis for infertility treatment. CNY Fertility Center in Syracuse NY, Albany, NY and Rochester, NY provide consultations, and treatments for couples trying to conceive.
The number of follicles, each containing one egg, which are available in the ovarian pool relates to the chance of success of In Vitro Fertilization (IVF). These numbers decline with age, and in some women decline abnormally fast. For couples who are trying to conceive and their care givers, methods of predicting the potential outcome of IVF can be important in making medical decisions.
One important tool for measuring the ovarian pool is a direct measure of the follicles as they emerge in a given month. The number of small follicles in the ovary during a menstrual period are observed using ultrasound. At this point there are no large follicles, and the pool of follicles which will emerge that month are beginning to grow. As the fluid accumulates, even a few milliliters (a teaspoonful is 5 ml) of fluid in the antral follicle can produce a measurable echo on the highly sensitive ultrasound machines used for transvaginal evaluation of the ovaries. Follicles between 2 and 5 mm can be visualized and counted. The antral follicle count (AFC) must be done when the follicles have not begun to grow. Thus it is scheduled day 2, 3 or 4 of the cycle prior to considering IUI or IVF therapy. Since there is not a huge variation from month to month, this test can give a good idea of the prognosis for the future.
Because not all of the follicles can be visualized , after stimulation by clomiphene or injectable gonadotropins, the number of follicles which eventually develop may be higher that the number of antral follicles in that particular cycle.
In a review of studies, Verkagen has concluded that the AFC is as good as any of the biochemical tests to determine ovarian reserve. In IVF treatment, if the AFC is less than 4, there is a much lower rate of successful pregnancies. Since this cut off is so low, this limits the value of the test. How high can it go? Egg donors or young infertility patients might have an antral follicle count of 17 or more. The typical mid-30 year old infertility patient will have 5-10 antral follicles. Sometimes in women with low ovarian reserve it is tempting to try to find a cycle with more antral follicles in order to get a slightly better result. However, there is low variability of the AFC from month to month (Jayaprakasan 2008) so waiting for another month is not likely to change much.
More indirect biomarkers of ovarian reserve include serum FSH, day 3 estradiol levels, inhibin B and anti-Mullarian hormone. These tests of ovarian reserve are covered in the section on IVF prognosis on this web site. In practice all available information is used for prognosis. Thus, the AFC is used in conjunction with the indirect tests of ovarian reserve.
For additional information and opportunities to get involved in infertility chat rooms, visit CNY Fertility Center’s patient discussion forums for medical questions or support.
Verkagen et al Fertil Steril 2008
Jayaprakasan, K et al. Establishing the intercycle variability of ultrasonographic predictors of ovarian reserve. Fertil Steril 2008;90:2126-2151.
Edited by JBM on 9-26-09