No nasal bone and high NT

[Simz01]

Hi All,

I am currently nearly 14 weeks pregnant with fraternal twins.

Our 11+3 week scan showed a high NT of 2.9mm and absent nasal bone for one of the twins. At 13 weeks it was the same, and put baby in high risk for Downs or other chromosome abnormalities. We were advised to do CVS test, which we did. The first set of results came back clear for Trisomy 13, 18, 21.

We have now been referred to do a fetal echo scan to check the heart in detail.

Has anyone had this? Or what else could the high NT and absent nasal bone indicate? The nasal bone really worries me

Tia

No experience re the absent nasal bone, but my son's NT was 2.7mm so just under yours and it wasn't even mentioned as being high? My understanding was that anything under 3.5mm was in the 'normal' range? It's good your CVS has come back clear, hopefully all it well but I appreciate it must be a worry.

Are you in the UK? As @Aria2015 says the measurement of 3.5mm is the UK standard point for advising further investigation. I assume it is very different for the other twin?
Some people have a nasal bone, others do not. It is a finding which is fairly common in those with Down’s syndrome but many with “normal” chromosomes do not have one either. It is just human variation. It is not a reliable indicator of Down’s syndrome which is why it is not routinely used in screening. It is a chance finding which can increase suspicion if there are other “soft” (ie non-diagnostic) signs seen.
It is very good to hear that the initial CVS result shows normal chromosomes. The heart scan is to rule out a “plumbing issue” as the reason for a relatively increased NT.
Hope you get reassurance very soon

If you are in the UK (or can get here) and can afford to, can I recommend you go to see the team at:

fetalmedicine.com/

They are absolutely amazing and very skilled at diagnosing in utero etc.

They can also refer you back into the NHS (and help with that) if you need to.

@Aria2015 thank you so much , that is reassuring to hear. I didn’t realise about the 3.5mm and maybe it was raised due to combination of that and not a visible nasal bone

@Sussexmidwife, thank you, that’s really helpful. They were both soft markers , and due to combination of both , the cvs was suggested. We did the harmony but it came back inconclusive due to not enough fetal dna. That’s right, the other twin NT is 1.4mm with nasal bone visible. That’s very useful to know re the heart scan , thank you.

@testingtesting101 I emailed them just today actually. The Dr was really kind and came back to me personally and suggested a detailed 20 week scan which I will book in for

So glad you called them, they were utterly amazing with all my pregnancies (including picking up the issues with one baby that had been missed on an NHS scan....).

@testingtesting101 thank you. They sound really good and thorough, so looking forward to detailed scan x