20 week scan question…

[Emerald234]

Hello,

So I've just joined and was looking for a bit of advice... I had my 20 week scan today - all looked fine, the sonographer said everything was developing normally. When I got home I noted that one measurement of baby was very small. This was the Cisterna Magna (CM) measurement in the brain. I am 19+6 weeks exactly, and the CM measurement was 2.8mm. It was so small it was off the end of the little scale they provide.

This has got me a bit worried, but looking it up there isn't much information small CM measurements - this is quite a lot of info on if the measurement is too big. I plan to call my midwife on Monday to ask about it as well but wondered if anyone else has experienced this?

It's my first baby and all I seem to do is worry! The head circumference and all other brain measurements seem in the normal range. Thank you all in advance 🙂

I don’t have any experience of this. But some of the measurements at one of my scans looked a bit off to me. The head circumference was off the scale large and the rate of blood travelling to the brain was slow. I asked the sonographer about it at my next appointment. She said that all the measurements were estimates and particularly in early pregnancy, an estimate that is 1mm out will make a huge variance on the scale.

As it turns out my dd does have a slightly larger than average head. I probably wouldn’t be aware of it if I hadn’t seen it on the breakdown of measurements.

I know this is not particularly close to your situation but I just want to assure you the measurements are just estimates and averages are just averages. Something may easily look a bit off when in fact, it’s perfectly fine.

If the sonographer was in any way concerned by a measurement, especially one in the brain, they would have reffered to to fetal medicine as a matter of urgency.

@vincettenoir

I don’t have any experience of this. But some of the measurements at one of my scans looked a bit off to me. The head circumference was off the scale large and the rate of blood travelling to the brain was slow. I asked the sonographer about it at my next appointment. She said that all the measurements were estimates and particularly in early pregnancy, an estimate that is 1mm out will make a huge variance on the scale.

As it turns out my dd does have a slightly larger than average head. I probably wouldn’t be aware of it if I hadn’t seen it on the breakdown of measurements.

I know this is not particularly close to your situation but I just want to assure you the measurements are just estimates and averages are just averages. Something may easily look a bit off when in fact, it’s perfectly fine.

Thank you very much - that is really helpful to know. It is such a tiny measurement - 2.8mm! I'm feeling more reassured now having done a bit more research into it too

@HeyFloof

If the sonographer was in any way concerned by a measurement, especially one in the brain, they would have reffered to to fetal medicine as a matter of urgency.

Thank you - that's good to know too, and that makes total sense. I think I just saw the report, and the measurement off the scale and freaked out a bit!

As far as I know the baby grows so rapidly at this stage, these measurements can change in a few days/weeks. They would of said it if something looked alarming. Ask your midwife for a piece of mind, but I'm sure everything is fine with your baby 🙂

@Emerald234 hi dear, hope you and baby are well. I know it's been a while since you posted this but I have a similar issue to yours with a CM on the smaller side at 21 weeks...Just wondering how you got on and hoping all was well with baby in the end ?