An Antral Follicle Count (AFC) ultrasound is a non-invasive diagnostic imaging procedure used to evaluate a woman's ovarian reserve, which indicates the remaining supply of her eggs. The scan is typically performed via a transvaginal ultrasound during the early follicular phase of the menstrual cycle, generally between days two and five, when the ovaries are most quiescent.

During the exam, a fertility specialist or sonographer utilizes high-frequency sound waves to visually examine both ovaries. The primary goal is to manually count the number of antral follicles—small, fluid-filled sacs that measure between 2 and 10 millimeters in diameter. Each of these follicles contains an immature egg that has the potential to grow, mature, and be released during ovulation. On a traditional black-and-white ultrasound screen, these small follicles resemble a cluster of dark, circular spots within the denser tissue of the ovary.

The final count provides a reliable assessment of fertility potential. A higher count typically implies a robust ovarian reserve, suggesting a favorable response to ovarian stimulation treatments common in In Vitro Fertilization (IVF). Conversely, a low follicle count may point toward a diminished ovarian reserve, which helps specialists customize medication dosages for fertility treatments. In addition to assessing egg supply, the scan helps identify conditions like Polycystic Ovary Syndrome (PCOS), which is frequently characterized by an abnormally high concentration of small, underdeveloped follicles arranged around the periphery of the ovary.