The antral follicle count (AFR) is directly related to the possibility of obtaining a good ovarian response and a good number of eggs retrieved after controlled ovarian stimulation and inversely proportional to the woman's age.
This antral follicle count can be performed at any time during the cycle, although it is easier to perform it in the early follicular phase (at the beginning of the cycle, from the 2nd to the 5th day) since here the possibility of observing follicular cysts or corpus luteum (tissue formed after the egg is released from the ovarian follicle) is reduced.
The primordial follicles are those that initiate folliculogenesis in the ovary, evolving into primary, secondary or preantral follicles, not identifiable by ultrasound.
A proportion of follicles progress to antral follicles, sensitive to follicle stimulating hormone (FSH) and identifiable by ultrasound, and progressively have the possibility of reaching the preovulatory stage.
This follicular capital can be quantified through the determination of gonadotrophins (FSH, basal estradiol, luteinizing hormone), and especially by antimüllerian hormone (AMH), together with the quantification of the number of developing antral follicles in the ovary by transvaginal ultrasound.
Several authors agree that the antral follicle count by transvaginal ultrasound is the best predictor of response to assisted reproduction cycles.
We know that there is an important inverse correlation between the age of the patients and the antral follicle count. In a woman under 35 years of age, we should see a minimum of 10 antral follicles between the two ovaries by ultrasound to consider this follicular count normal and expect a normoresponse during an ovarian stimulation cycle for IVF.
A count below 5-7 antral follicles between the two ovaries is considered suggestive of low ovarian reserve.
From the age of 35, the first peak of ovarian reserve decline occurs and from here on, our reserve begins to decrease at a faster rate, so the antral follicle count will also begin to be lower as our ovarian reserve is lower.
