Detection of fetal anencephaly using real-time ultrasound.

Anencephaly can be diagnosed using real-time ultrasonography. This enables visualization of the fetal movements and facilitates identification of the fetal parts, making certain the exact orientation of the fetus. Thus, the negative finding of the lack of fetal calvarium, as well as the positive finding of insufficient space for a calvarium to exist between the fetal thorax and the uterine wall, can be confidently ascertained. One can then be certain that a fetal head is not being missed by the ultrasound beam, as is possible with a rapidly moving fetus using B-mode ultrasound.