A Follicle Tracking Scan / Antral Follicle Count (AFC) is carried out as part of fertility management. The number and size of your follicles are determined at each scan along with the thickness of the lining of the uterus (endometrial thickness).
A follicle is a fluid-filled sac in the ovary that contains eggs. By measuring the size of any active follicles, an estimation of when ovulation is likely to occur can be provided in women with both regular or irregular cycles. This helps increase the chances of conception, both naturally and with the help of fertility treatment. Generally, three follicle-tracking scans are required during any one menstrual cycle. The follicle tracking scan is administered internally (transvaginal ultrasound) in order to ensure maximum accuracy.
Monitoring the ovaries, follicles and ovulation is also commonly used during fertility treatment, such as in-vitro fertilization (IVF) assessment to determine the best time for intrauterine insemination. The fertility ultrasound assesses ovarian follicles at regular intervals and helps the obstetrician understand when you ovulate and when egg retrieval is best performed. Tracking will vary between individuals and their treatment plan but normally starts on the 10th day of the cycle.
Follicle tracking scans are often administered for the following reasons:
- To assist in managing infertility treatments, such as IVF/IUI, by measuring the size of the follicles and endometrial thickness.
- For patients who have regular cycles and have been trying to fall pregnant for several months without success.
- For patients who have irregular cycles and want help determining the best time to conceive naturally.
As well as looking at the ovaries, the follicle tracking scan will also measure the endometrial thickness (lining of the uterus), as this will influence whether the embryo will be able to implant. The thickness of the endometrium needs to be 7 mm plus to be suitable for pregnancy to implant.
