Can ultrasonography replace amniocentesis in fetal gender determination during the early second trimester?

Fetal gender was prospectively determined by ultrasonography in 115 patients with singleton pregnancies between 16 and 20 weeks of gestation. Gender determination was performed as a part of the sonographic examination preceding genetic amniocentesis, and the results were compared to the amniotic fluid fetal karyotype results. Our rate of visualization of the fetal external genitalia was 83.5%. The accuracy rate for gender determination was 90% in male infants and 100% in female infants, with an overall rate of prediction of 92.7%.