T21 risk much greater than T13/18

[piechipsgravy]

Hello,

I got my 12 week screening results back yesterday (taken at 13+0). I'm 29 (will be 30 this month).

T13/18 was 1:5000
T21 was 1:284
NT was 2.3mm

While that is still classed as 'low risk' there is obviously a big difference between the two results and I'm struggling to understand what could have triggered such a relatively high number for T21 when it doesn't correlate to my age and the NT was within range.

Has anybody had similar who could shed some light?

Thanks

It's based on the blood results as well. T21 risk is elevated when hcg is on the higher end so if guess its that. T13/18 elevates when hcg and papp a are low, so that's why the risk is different. It's still low though, and the combined screen is just an algorithm based on averages. Theres a really wide range of 'normal' hcg and on its own doesn't mean much other than indicating that you are pregnant. Congratulations!

@piechipsgravy this graph helped me understand.
You can see how different levels of PAPP-A and hCGb correlate to the likelihood of different Trisomys.

My combined screening test came back as 1/143 risk for T21.

My results were:
NT 1.6mm
PAPP-A 0.52 MoM
hCGb 3.31 MoM

I hope this helps

Thanks so much @Chasingbaby2 @crimpdad

For anyone reading this thread in the future, I rang the screening department they told me my results were:

NT 2.3mm
HCG 1.77 MOM
Papp-A 0.49

All 3 measures in the normal range but following the trend of T21, hence the increased risk.

@piechipsgravy I've just had results very similar yours, t21 is 1 in 207 and t13/18 1 in 41,000! My NT and blood measurements are very similar too. I'm considering getting an NIPT test to ease my mind, I wondered if you did that or if you are feeling fine about everything now?

@ab03 we decided not to get the NIPT in the end as we wouldn't terminate for DS anyway and figured if there were health related complications these would be picked up at 20 week scan.

I'm 28 weeks now and had scans at 20, 24 and 28 weeks (24 and 28 for something unrelated to this!) and baby has looked healthy with no concerns at all of these. Obviously I can't say that whether they do or do not have DS until they are here but I know there are currently no concerns with their heart, growth or any other development. I rarely think about my screening results now to be honest!

Hi OP @piechipsgravy hope you are well! Hope you don’t mind me asking how things ended up for you in the end? Xx

@LAURAPAX baby girl was born in November perfectly healthy and no DS ☺️