The use of three-dimensional ultrasound for fetal gender determination in the first trimester

The objective of this study was to examine the accuracy of fetal gender prediction at a routine first trimester scan using three-dimensional (3D) ultrasound. 200 women were recruited for this study and they agreed to have a transvaginal scan for their routine first trimester scan for fetal anatomy and nuchal thickness measurement. 3D volumes were obtained and stored. Two examiners independently reviewed all the volumes and recorded their diagnosis of fetal gender and measured the angle between the genital tubercle and the skin overlying the sacrum. After studying the 3D volumes both examiners recorded a diagnosis of male or female in 150 cases (81.5%). In 34 cases (18.5%) either both (n=21) or one of them (n=13) could not comment on fetal gender by studying the saved volume. From these 150 cases correct prediction of fetal gender by both examiners was achieved in 85.3% of cases. In 6.7% of cases both examiners predicted the wrong gender while for the rest 8% of cases each examiner assigned different gender to the fetus (k=0.84; standard error 0.045). Angle measurements performed from the saved 3D volumes were highly reproducible. Gestational age did not affect the accuracy of gender identification. This study demonstrates that 3D ultrasound can be an effective and fast way of identifying fetal gender in the first trimester. The advantages of 3D ultrasound stem from its ability to virtually reproduce all required views.