OC80: First‐trimester determination of fetal gender by ultrasound

To determine the feasibility of correctly identifying fetal gender from 11 to 13 weeks of gestation using two-dimensional and three-dimensional ultrasound. Fetal gender assessment by ultrasound was prospectively carried out in 695 singleton pregnancies at 11–13 weeks of gestation (confirmed by crown–rump length or biparietal diameter) immediately before chorionic villus sampling for karyotyping. A total of 720 women underwent a detailed assessment of fetal anatomy at 11–13 weeks of gestation using transabdominal and transvaginal sonography, first 2D ultrasound and afterwards 3D ultrasound. Fetal gender was identified in transverse and sagittal planes, and was confirmed by chorionic villus sampling. Fetal gender assignment was possible in 695 of the 720 (96.5%) examined fetuses. The accuracy of gender determination using two-dimensional ultrasound increased with gestation from 94% at 11 weeks, to 96.6% at 12 weeks and 98.8% at 13 weeks. Male gender was wrongly assigned as female in 5.5% of cases at 11 weeks, 2.4% at 12 weeks and 0% at 13 weeks. The accuracy of gender determination using three-dimensional ultrasound increased with gestation from 80% at 11 weeks, to 85.2% at 12 weeks and 93% at 13 weeks. Female fetuses were diagnosed early in 13 women with hemophilia and in 10 women with neuromuscular disease, and so early invasive procedures were not performed. The accuracy of correctly identifying fetal gender increased with gestational age. Two-dimensional ultrasound is better for early diagnosis of fetal gender than three-dimensional ultrasound. Early diagnosis of fetal gender can help ultrasound avoid unnecessary invasive procedures in women with hemophilia and neuromuscular diseases.