Yes, it is possible miss the sex of the baby with the ultrasound. Depending on the time of pregnancy and the position of the fetus, the doctor may be mistaken.
If the ultrasound indicates that the baby is a boy, and more difficult the doctor is wrong because he can see the penis by ultrasound.
When is girl, you can not see the vagina and so there is more likely to be mistaken in relation to the sex of the baby. The fact that the doctor does not see the genital organ does not properly mean that it is a girl, since the gestational week and the position of the fetus may interfere with viewing.
Through transvaginal ultrasound it is possible to know if the baby is a boy or girl from the 13th week gestation. However, there is still a 20% chance of error, depending on fetal position and placental implantation.
From the 16th week pregnancy is already harder to miss the baby's sex, but it can happen.
