A transvaginal ultrasound scan performed during the early part of the menstrual cycle can be used to assess ovarian reserve. This scan is used to count the total number of small antral follicles present in both ovaries. This count is known as an antral follicle count (AFC) and provides an indirect measure of the total follicular pool in the ovaries. For more information on ovarian follicles and antral follicles, see my section on The Menstrual Cycle and Ovulation Tracking.
Other markers have been used to estimate ovarian reserve including blood tests for measuring the levels of FSH and inhibin B. However, AMH and antral follicle counts are the two best tests available.