prenatal US shows enlarged 4th Ventricle/Cisterna Magna

I had prenatal ultrasounds at 16 weeks and 20 weeks that showed a slightly enlarged fourth ventricle and cisterna magna.  The values were apparently just above normal and the ultrasounds showed no other anomalies.  The doctors assured me it was probably nothing but referred me to a neurologist (appointment still 6 weeks away).  I've done my own research on what this might mean-which is a little scary obviously and the wait to my next appointment is proving unbearable.  Any thoughts on implications of this and is it really possible that this is just an invitro developmental abnomally that will resolve by birth?

Thanks in advance!

[PaulMD]

Hi there.

The fetus is continuously developing, and the greatest developments are happening with the brain of the fetus.  These findings may just be transitional changes in the brain brought about by this rapid development.  The most important thing to do is to relax, and have this evaluated by the neurologist as your doctor advised.  Disappearance of these findings may also be at hand during the next visit, or next ultrasound.

It is best to continue your vitamins and mineral supplements, especially folic acid, since studies show that this would prevent or lessen the risk of neurologic abnormalities in the developing fetus.

Regards.