Which vascular strucure is abnormally dilated in this condition?
The median prosencephalic vein which is a precursor of the vein of Galen, not the vein of Galen itself.
What is the abnormality?
Vein of Galen malformation
What other antenatal abnormalities should be looked for, in these patients?
Fetal cardiomegaly due to the high output state, and fetal hydrops if cardiac insufficiency ensues.
Greyscale ultrasound image shows a prominent anechoic, midline structure within the fetal head. Doppler assessment demonstrates prominent, turbulent flow within it, with a low resistance waveform.