High risk blood tests in pregnancy

[onanislandfaraway]

Posting for traffic sorry. I’m 14 weeks pregnant and had a phone call today at work to say my blood test for Down’s syndrome, Edwards’ syndrome or Patau’s syndrome came back high risk. They wanted me to come in as soon as possible for more blood tests so I’m booked in for tomorrow. I held it together through my shift but not long come home and it’s hit me like a tonne of bricks.

I wasn’t really thinking straight on the phone call, it was right in the middle of a stressful busy shift which obviously didn’t help. The test they will do tomorrow is 97% accurate. I asked her how accurate this test was but I don’t think I understood correct. From what I remember she said 85% chance, so I was thinking the test is 85% chance of being correct for high risk. I forgot the results were normally given as a ratio so didn’t ask her what they said but she kept saying one in 15 women with this result will be OK. I don’t think that sunk in there and then. I’ve just come home and told my partner and when I said I’m confused about the percentage as it should be a ratio, he mentioned 85% being 1 in 1.15 and it hit me, is this what she meant? So the test itself isn’t just 85% accurate for detecting a high risk, what she meant was my ratio is pretty much saying my baby has a 14/15 chance it has one of the syndromes tested.

I’m sorry if I’m not making sense, I can’t really think straight especially after my shift and trying to pretend that everything is fine because we were so short staffed and I was the only nurse on, now I'm home I can't hold it together. I just can’t get my head around these figures. 85% as a ratio is 17:20! People are deemed high risk even with 1 in 150 aren’t they? So surely 17:20 chance is almost a definite the baby has a condition. I know I’ll find out more tomorrow but I was just wondering if anyone can shed some light on the figures? Or has anyone been in this situation or has known of such a high result?

Really you can only wait until tomorrow. Try and get some sleep and don’t Google. I wish you luck for tomorrow. Remember there is still a chance your baby is absolutely fine.

I don’t think that’s what your midwife was saying - the highest odds you can get is 1:2. I think she meant 85% of downs cases are picked up by the test, but the test will pick up many many more cases that aren’t downs but have a couple of measurements that may point towards it. Good luck!

Thank you both. I doubt I'll sleep, I'm wired!

I didn't mean to enable voting. That's give me a little hope that the highest odds is 1:2, I thought those odds sounded so odd, I'm sure I heard her repeating the 1 in 15 thing though but then again I don't think I was processing it properly then. Had my first scan last week, they said all looks good, NT measured 1.7mm so it's just such a punch in the gut.

Sorry you’re going through this. I had exactly the same. However I’m a statistician and ended up giving the poor nurse a whole lecture about what the results meant and how they should be presented. Telling you it’s 85% accurate makes no sense when you get a probability (or odds) of something occurring. I think I worked out that, as a PP says, the 85% refers to the percent of downs cases that will be classified as high risk so it’s not even that great a test. If you odds are 1 in 15 that’s actually estimating a less than 7% chance there is a problem. This is just a screening test and I was high risk basically because of my age and one measurement being at the edge of the normal range. Went from 1 in 30 risk to 1 in 10,000 with the second blood test (NIPP test) and absolutely no problems. Hope you got some sleep and get the results you want soon.

Thank you NeverWearingHeelsAgain. Sorry you went through something similar, happy to hear all was well in the end.

I feel a lot more relieved today. I'm surprised I didn't prod for more information on figures either, I think I was just in shock and such bad timing in work. I'm surprised I don't know a bit more about this, especially as this is my third pregnancy and I'm the sort that likes to research every detail! Maybe it's because my other pregnancies have come back low risk. I was even confused with what tests I had, thinking I may have already had the NIPT tests (when it was the combined) and learning how accurate they are just had me worrying unnecessarily.

It was a confusing phone conversation but the midwife was lovely today and explained it better. I actually have a 1 in 69 chance of Down's and 1 in 10,000 chance of Edward's and Patau's syndrome. So not as bad as I thought and I have had the NIPT test done today, very lucky we get it on the NHS in Wales as I don't know if that's the case elsewhere. Should hear by Thursday. My results on the combined test were:

hCGb 4.05 (128ng/mL)

PAPP-A 0.63 (2479mU/L)

NT 0.91 (1.7mm)

I'll be just over 35yo on delivery.

She did say that the only result that was out was my HCG although I have seen elsewhere that ideally the PAPP-A should also be above 1 but she did say it was just my age and HCG levels producing the high chance. So I will hopefully have more answers Thursday but for now I'm feeling at least a little less anxious about it. I'll update on Thursday as hopefully this may help someone else.