AFC (Antral Follicle Count)

During a baseline transvaginal ultrasound (typically done on cycle days 2–4), a sonographer counts follicles measuring 2–10 mm in each ovary. These antral follicles represent the pool of eggs that could respond to stimulation medication that cycle.

A total count of 10–20 is generally considered normal. Fewer than 7 may indicate diminished ovarian reserve, while more than 20 raises concern for PCOS and hyperstimulation risk. AFC is used alongside AMH and FSH to decide starting gonadotropin doses for IVF stimulation.