Risk of Down's from combined screening - can this be right?

[BeadyEyes]

I got a letter today that said that my risk of Down's is less than 1 in 10,000, based on the nuchal scan and blood test.

Obviously I'm very happy with this result, but wondered if it is correct? I am 35 (36 when baby will be born), and the scan dated me at 12 weeks 6 days (which I think is 5 days ahead, but I am not sure if that it relevant). I had the blood taken on the same day. The nuchal measurement was 2.4mm which I thought was on the high side of average. I have a BMI of about 22, and am from a non-smoking, mixed Western European/English ethnic background.

Anyway, I thought that for my age the risk was about 1 in 350, so am wondering if they might have made a mistake calculating my odds? I am (obviously) not scientifically minded, but is it possible that the odds are so low in my case?

If anyone could share their wisdom, I'd be very grateful. Please forgive me if my question is silly - I'm new to all of this pregnancy stuff!

Yes of course than can be accurate. If it was only based on age then they wouldn't bother with the bloods etc.

Mine when I was pregnant with DS2 and aged 33 was about 1 in 30,000.

Be pleased! And relax, I'm very sure it isn't a mistake :)

It does seem a great result from a 2.4mm nuchal. I had a 3.1mm nuchal and perfect bloods (both GCG and Papp A were 1.0 MoM) and we got a 1 in 10 measurement. I'm a year younger than you too. However, the it's a complicated equation and most likely 1 in 10000 is right. Do you know if they considered the heart valves, nasal bone a d liver flow (Kins in London and some private clinics factor these in) if so, and if those things were looking good, that would explain things.

I'm 18 & mine was 1 in 950. They use bloods & measurement to calculate your risk, although statistically high because of your age it's not actually a factor. Prepared to get told this is wrong by sciencey's
Also my nuchal measurement was 3.2mm which I believe is quite high.

HTH

I'm 38 and my risk based on nuchal fold and bloods cane back at 1pm 100,000 so yes I can't see why yours would be wrong.

1 in not 1pm!

Im exactly the same age and bmi as op, my nuchal fold was 1.8mm and I was 12 wks exactly. My result was 1 in 1800 so I presume that means my blood results weren't really good?

Hi all,

Thanks for your advice! As I am slightly insane at the best of times a bit of a worrier I ended up ringing the number on the letter and asking the people at the scanning department about the results. Thought I'd share what they said in case it's of any help to anyone else...

Apparently, the nuchal measurement itself is looked at in relation to the crown-rump length of the baby - my baby was fairly long, so the measurement of 2.4mm was not concerning. I also had very low risk blood results, which brought the overall risk right down. The person I spoke to was lovely and helpful.

By the way, my hospital (a tertiary NHS hospital) doesn't take the nasal bone into consideration, although I did see on the scan what appeared to be a nasal bone.

Thanks again for your advice!

My understanding is that your 1 in 350 isn't your actual risk for having DS, but it's the risk that your combined assessment will come back as high risk. I too am 35 and took a bit of getting my head round how the numbers work. Not sure I've explained it very well, but does that make any sense?

I was 39 when I had dd2 and my risk from combined test was given as 1 in 72000!

Well, mine was 1 in 150 and I was 25 at the time. And I asked for the test not to be done :( I don't think age is a massive factor ... Sounds like a good result

I am 34 and mine came back as 1 in 9000 which is very good for my age I know. I actually checked with mw as I thought could be a mistake and she said no it's fine. Many women have even more promising results.