P01.45: Fetal gender screening by ultrasound at 11–13+6 weeks

Abstract

To survey the accuracy of fetal gender determination during the first-trimester screening and scan for congenital anomalies. A prospective observational study was performed on 496 singleton pregnancies at the first-trimester ultrasound screening. The doctor was certified by The Fetal Medicine Foundation (FMF). Ultrasound examination was performed on a GE Voluson 730 Pro transabdominally between 11–13 + 6 weeks. Both transverse and mid-sagittal planes of section of the fetal genital tubercle were done to identify the gender. The subsequent gender at birth was obtained from the karyotyping reports or the hospital birth records. During the study 496 patients requested gender information at the time of first-trimester screening. Of those patients where it was possible to determine gender (441 out of 496) the scan achieved an overall success rate of 92.3% in correctly identifying gender. It was found that both transverse and mid-sagittal planes to identify fetal gender were necessary to improve determination. When the crown-rump length was 45.0–56.0 mm, the accuracy rate was 75.4%, when the crown-rump length was 57.0–67.0 mm, the accuracy rate was 92.0% (P < 0.001), when the crown-rump length was 68.0–84.0 mm, the accuracy rate was rose to 98.3% (P < 0.001). The fetal gender accuracy rate for male fetus was slightly better than female (93.4% vs 91.2%) but is not statistically significant. This study demonstrated that the 11–13 + 6 weeks scan achieved an overall adjusted accuracy of 82.1% in correctly determining fetus gender. The gestation age of the fetus had a material effect on the accuracy rate of gender determination.