#1 What tests are part of an ovarian reserve assessment? What is their utility?
FSH and estradiol
Follicle-stimulating hormone (FSH) and estradiol should be checked together in the early follicular phase (days 2 to 4 of the cycle). Elevated levels of one or both hormones suggest diminished ovarian reserve; an FSH level greater than 10 mIU/mL and/or an estradiol level greater than 80 pg/mL represent abnormal results6 (TABLE 1). Because FSH demonstrates significant intercycle variability, a single abnormal result should be confirmed in a subsequent cycle.7
Although the basal FSH level does not reflect egg quality or predict natural fecundity, an elevated FSH level predicts poor ovarian response (<3 or 4 eggs retrieved) to ovarian hyperstimulation, with good specificity.3,6,8,9 In patients younger than age 35 years undergoing IVF, basal FSH levels do not predict live birth or pregnancy loss.10 In older patients undergoing IVF, however, an elevated FSH level is associated with a reduced live birth rate (a 5% reduction in women <40 years to a 26% reduction in women >42 years) and a higher miscarriage rate, reflecting the positive correlation of oocyte aneuploidy and age.
In addition to high intercycle variability, an FSH level is reliable only in the setting of normal hypothalamic and pituitary function.7 Conditions such a prolactinoma (or other causes of hyperprolactinemia), other intracranial masses, prior central radiation, hormone-based medication use, and inadequate energy reserve (as the result of anorexia nervosa, resulting in hypothalamic suppression), might result in a low or inappropriately normal FSH level that does not reflect ovarian function.11
Antral follicle count
Antral follicle count (AFC) is defined as the total number of follicles measuring 2 to 10 mm, in both ovaries, in the early follicular phase (days 2 to 4 of the cycle). A count of fewer than 6 to 10 antral follicles in total is considered consistent with diminished ovarian reserve6,12,13 (TABLE 1). Antral follicle count is not predictive of natural fecundity but, rather, projects ovarian response during IVF. Antral follicle count has been shown to decrease by 5% a year with increasing age among women with or without infertility.14
Studies have highlighted concerns regarding interobserver and intraobserver variability in determining the AFC but, in experienced hands, the AFC is a reliable test of ovarian reserve.15,16 Visualization of antral follicles can be compromised in obese patients.11 Conversely, AFC sometimes also overestimates ovarian reserve, because atretic follicles might be included in the count.11,15 Last, AFC is reduced in patients who take a hormone-based medication but recovers with cessation of the medication.17 Ideally, a woman should stop all hormone-based medications for 2 or 3 months (≥2 or 3 spontaneous cycles) before AFC is measured.
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