Can someone explain please, if the NT measurement is within normal range, why are some people still given a 'high chance' statistic.?

[Ashleys63]

It's not me, although it was many years ago.
it's just something I've never really understood, surely if the NT measurement is within normal range why the need for any further tests? I see it on here time and time again, women with normal nt measurements yet getting 'high risk' screening results? it just leads to so much worry (and, what seems like. in the vast majority of cases, unnecessary further testing).
Maybe a midwife can explain.?

Based on blood tests that are done at the same time !

Also she factors in too

Age !

Because the NT measurement isn't taken in isolation or the only indicator of problems. That's why you have the blood tests alongside.

The thing is having babies is a risky business , there are a myriad of things that can go wrong ..
They only give you the info so you can make decisions based on that .. it's probability !

Thank you.

The Combined Screening Test takes your age, ethnicity, biochemical markers (PAPP-A and Beta HCG) and the NT measurement and a computer program is used with an algorithm that calculates the chance of you having a baby with trisomy 13&18 or 21 based on these results.

This is why you can have a woman who has a normal NT and a very low 'background risk' (age alone) who has a high chance result because the biochemistry has made a big impact. Or a woman with a high background risk because of age, who has a lower chance result because her measurements and biochemistry indicate it is much less likely that the baby is affected.

Nt is not the only indicator of issues
There are many many other conditions beyond trisomy 13&18 or 21

My child had normal NT and low chance screening results but was born with Down syndrome. It’s screening, not diagnostic.

I’m pleased they got it wrong if I’m honest. She’s totally fabulous.