Ovarian Follicle Evaluation: Antral Follicle Count and Follicle Monitoring During Controlled Ovarian Stimulation

Transvaginal Ultrasound (TVUS) is widely used to assess the number and the size of the follicles in clinical practice, particularly for women undergoing assisted reproductive techniques (ART). The antral follicle count (AFC) is defined by the number of follicles considering both ovaries by TVUS and it is mainly used to assess woman´s functional ovarian reserve, which is useful to predict the ovarian responsiveness to controlled ovarian stimulation (COS) with gonadotropins. During COS, monitoring of follicle growth helps on: cancelation of cycles, appropriate time to trigger final follicular maturation and assessment of the risk of OHSS (ovarian hyperstimulation syndrome). Traditionally, follicle counting and measuring are performed by two-dimensional TVUS, but the use of three-dimensional TVUS allows faster acquisition time and standardized evaluation; additionally it provides additional features as the multiplanar view, volume contract imaging (VCI) and Sono-Automatic Volume Calculation (SonoAVC), which might help improving the reliability of follicle count and measurement.