Right ventricle of baby's brain - measuring 10 mm at 20 wk u/s

[AMS04]

Hello - I just had my 20 week ultrasound.  My doctor said everything looked perfect except for one "minor" concern.  The right ventricle in the baby's brain is measuring 10 mm, which she indicated is still within the "normal" range, but since it's at the top end of the normal range, she wants me to get a level 2 u/s and talk to a high-risk OB.  She said they are just being careful and want to make sure the width of the ventricle does not increase, as anything over 10 mm could be a sign of fluid building up on the brain.  We are trying to remain calm and remind ourselves that our baby's ventricle is still "normal", but thinking about the potential of hydrocephalus is terrifying.  I should also tell you that we have had 1st and 2nd semester genetic testing (for Downs Syndrome and other chromosomal abnormalities) performed already, and everything was normal.  Nothing else out of the ordinary was found on the u/s, either.  Is this very concerning or more precautionary?  Is it likely that a fetus with hydrocephalus would have measurements greater than 10 mm at 20 weeks gestation?  Thank you for your help!!

[Elaine Brown, MD]

Hi!
Congratulations on your pregnancy!
I think your doctor is being precautionary, and I think she is doing the absolute correct thing by referring you for a level 2 scan.  There is a big difference in the technology between the scans in many cases--a big enough difference that your baby's ventricle may not even look "borderline" on the level 2 scan.  With different measurements it may fall totally within the normal range.

In most perinatologists' offices, the doctor himself will attend or even perform the scan, and this is a huge advantage to the person who is interpreting the scan because they can spend as much time as necessary taking measurements of various parts of the anatomy and looking at them from different angles. It is also amazing the detail that they can see on the more powerful equipment.

I am going to bet that you will be very reasurred by your visit, but I am also going to bet that you will have to have some follow up scans to watch the ventricle over time, so be prepared for that too. Even in the worst case scenario, if hydrocephalus does develop, knowing about it ahead of time can prevent most of the major complications from occuring.  I DON"T think you are going to face that however.

You might also request a 3d picture or two of your baby's face while you're at it!

Good luck!
Dr B

[HarryW5]

Dear Dr. Brown and AMS04,

I have a very similar situation going on, except my ultrasound was done at 22 weeks.  I am trying to remain calm about this as my baby is measuring at 10mm as well and everything else looked fine according to my OB/GYN.  We also had the genetic testing and everything came back fine.  I have been trying to do some research on causes of this and cannot find any info.  Is there a known cause?  I'm also wondering how common it is to have this situation (borderline measuring over) and what actions are typically taken in the event that the fluid in the ventrical increases?  

We have scheduled a detailed ultrasound followed by a consultation with a perinatologist next week, but the wait is going to wear on us greatly.  I know that as a first-time mother I tend to worry a little more about these things, but this is terrifying to me.  Any additional information would be greatly appreciated.  

And good luck to you AMS04!

[AMS04]

Hi Dr. Brown,

Your response was VERY helpful and reassuring, thank you.  If you don't mind, I have one follow-up question...would there be other signs and/or would the ventricle most likely have a measurement greater than 10 mm if it was hydrocephalus?

Thanks again,
Maria

[AMS04]

Hi Dr. Brown - Thank you; your response is very reassuring!

Have a great weekend,
Maria