Nuchal Translucency

saral1717 · July 2019

I am 35 (will be 36 when baby is born) and with my NT or 2.6-2.7mm (13 weeks 0 days) and bloods (hcg .84 mom and Papp-a .94 mom) I came back with a 1 in 194 for Down syndrome risk. I think it was my age and NT that pushed the results as I don’t think my bloods seem that bad?? I did the harmony test prior at 10 weeks 4 days and got a less in 1 in 10,000 for all 3 trisomies. I will get a cardiac scan when I am around 6 months. My doctor did not advise any additional testing because of my harmony test results and he believes that it is way more reliable than the scan and combined blood tests. Great right? So my concern is this I had a son who was born with a very rare cardiac birth defect and once you are that 1 in 10,000 you can’t help to hear no matter what .... that there is a chance not matter how small. The harmony test only detected 7.3% fetal dna - prob because I had it so early. There is also some discrepancy as to when I know I conceived and the size my baby is registering on the scan. I believe I am reading 4-5 days sooner. So with an early harmony tests done with low fetal dna is it that reliable? Am I just over thinking it and panicking because of what I went through in my last pregnancy? Would you get an Amnio? Any advice and stories are needed! Thank you for reading my post.

mercury94 · July 2019

So, my NT scan for my son came back high risk for T13 and T18. Had the NIPT and it came back normal. DS does not have T13 or T18. I would trust the NIPT over the NT any day. The NT is far less accurate and doesn’t check fetal DNA at all. I probably would not get an amnio unless encouraged to do so by my doctor. But, down syndrome would not have an impact on my decision to continue a pregnancy, so I’m not sure that I would really NEED to know in advance if my child had down syndrome.

saral1717 · July 2019

Thank you for your reply. Do you know why your NT test came back positive for the other trisomies and not Down syndrome? I’m guessing it must have been your bloods test. Also do you recall what your NT was? When your son was finally born did you have any other tests done to confirm the risky NT score wasn’t because of something else? I would like to be as prepared as possible if there is anything I need to be prepared for before she arrives.

mercury94 · July 2019

I don’t remember any measurements. It was over 2 years ago. I do remember seeing that the indicators related to hCG beta (in your blood) for T21 (Downs) are basically the opposite as T13 and T18. I assume that’s why it can up high risk for those 2 and not downs. Regardless, the NIPT is far more accurate, so I would try not to worry if I were you. We haven’t had any further testing done since he was born as he has shown no signs of any trisomy. The NT blood draw tests your blood, not fetal DNA, so it might show an increased risk if you have a hormonal imbalance at the time. I have PCOS and was on medication when I conceived and until I was 14 weeks, so I have always assumed that had something to do with it. Can’t confirm that, though. The NT is also designed to catch risk factors, so that many more will come up high risk than will actually have trisomy.

saral1717 · July 2019

Thank you. It’s oddly comforting to know
other people have been through similar things. Glad your son was ok!

delujm0 · July 2019

@saral1717 I had an NT when i was 36. The "age risk" of DS at 36 years old is 1 in 225. Which means that with no data, that would be the overall risk. It sounds like your risk is only slightly elevated based on that, and the NIPT is a LOT more accurate, so if your doctor isn't worried about it, i wouldn't be worried about it either. With my test results, my risk for DS was 1 in 5600. With VERY SIMILAR test results during a pregnancy when i was 32, my risk wound up being 1 in 10000. When you are AMA, it is basically impossible to test as 1 in 10000 on the NT scan (though that was my result on the NIPT).

Many doctors don't even do the NT scan if you have had NIPT. The NIPT is a lot more reliable.

chichiphin · July 2019

Okay so I'm going to be the one who goes against what everyone else is saying here.

The NT Scan (edit to say i mean the ultrasound measuring the nuchal fold) is incredibly accurate in measuring an increased fold which is an indicator of multiple things. The way my geneticist described it is that an increased fold is usually 50% chromosome issue, 40% other issue (varying ranges of severity) and 10% normal, and will resolve. The larger the fold, the more likely there is a bigger issue. Our NT measurement was 7.... which is way out of the normal range.

The NIPT blood work is actually NOT the most accurate test you can get. It does look at dna fragments in moms blood, but also assigns a risk score - it is not solely looking at baby's DNA - you even mention your fragmentation score.

So when our fold was high, we immediately got an NIPT. Guess what - the NIPT result assigned a risk score of T13 as something minuscule as I was 28 at the time and did not have previously affected pregnancies. The fold size, taken in conjunction with other risk scores on the NIPT had to be calculated BY A HUMAN after my NIPT resulted. No paper would have given me an actual risk score.

SO in conclusion. One test over the other is actually not "the most accurate" - rather taking multiple diagnostic tools and looking at results in totality is ideal. The genetic counselors (spoke with 3) told me that the only way to be sure in the immediate future was with CVS with microarray or an amnio - this is because you actually testing the DNA that is purely from the pregnancy. Please please please speak to a genetic counselor to see if an amnio is appropriate for you and your pregnancy rather than going off of a bump board.

*steps off soapbox*

bows22 · July 2019

@saral1717 everything I came here to say @mercury94 and @delujm0 already covered. However to answer one of the questions you raised I will add that my DD did end up being diagnosed with something that may or may not be genetic (they did some testing and nothing came back but there’s no way to totally rule out the genetic component) and it has crossed my mind that maybe the elevated risk on the NT bloodwork picked up on that. But I really don’t think that’s the case. I totally understand your concern though. My DD’s diagnosis is also rare so even though she is totally fine now, the possibility of a future LO being diagnosed with something seems more real. I personally would not get an amnio unless a doctor recommended it.

Edit to remove NIPT thoughts based on @chichiphin’s great info.

bows22 · July 2019

@chichiphin thanks for setting us straight! I have never really heard of any of that before. My OB’s office definitely explained that the NT scan/bloodwork was just a calculation of risk and the NIPT was more definitive, but I guess they were over-simplifying it? Or maybe they explained it that way because my elevated risk from the NT was not because of the nuchal fold measurement?

Edit because it’s a scan not a scab

chichiphin · July 2019

@bows22 I bet it was that last part - the NT blood work is less accurate than the NIPT. The NT fold measurement is where you should really be pursuing further diagnostic testing, especially if there is any increase risk with NIPT.

leksiL · July 2019

@chichiphin thanks for sharing your knowledge - I have had my NIPT blood draw and after reading the first responses I was like, why am I going for an NT scan?

congrats on your BFP this month!

OP hope everything turns out all right for you.

crazypuglady · July 2019

@saral1717 I'm 35 and I did both NT and NIPT. My Dr wouldn't even do the blood portion of the NT because I had said I had the NIPT done. I've also heard that the NT has a higher rate of false positives. If your Dr isn't concerned, I wouldn't pursue further testing. (But that's me. I understand being in your situation makes you want to be more cautious.) I know there is a risk with amnio or CVS, but if it brings you piece of mind, it may be worth it.You can always seek a second medical opinion.

mercury94 · July 2019

After @chichiphin’s comments, I think I’m changing my stance on not getting the NT scan in future pregnancies. Maybe I can just get the ultrasound and not the bloodwork. In my case, it was the bloodwork that made me high risk, not the measurement. I didn’t realize how important that measurement might be.

stassischroeder · July 2019

Thank you @chichiphin! I was considering skipping the NT scan and just doing NIPT this pregnancy until I read your response! Now I will insist on getting both again.

chichiphin · July 2019

@mercury94 @stassischroeder this has become a huge advocacy thing for me since our loss. Even my own OB was flaky on the details which is kind of scary. The MFM and geneticists were there ones who clearly articulated any of this to my husband and I.

saral1717 · July 2019

Thank you all for your comments and sharing. My sonographer told me everything looked “perfect” and was “normal”. She was not concerned with the 2.6-2.7mm NT measurement. She asked if I had the NIPT done I said yes and she went on with small talk about how some offices don’t even do the NT sonogram and blood test anymore and only offer the NIPT. It wasn’t until after I spoke to the doctor that he said I was on the higher “normal” side for the NT measurement. He then looked at my NIPT test and said “oh it came back low risk I wouldn't have the amnio I think that would be over kill but it is ultimately your decision”. He told me before the NIPT was available he used to do about 80 amnio procedures a year and now he does about 5. It sounds like many of you on this post still do believe the NT measurement has some significance to identifying abnormalities. Would you all be concerned with a measurement of 2.7mm?

chichiphin · July 2019

@saral1717 I would speak with a genetic counselor as they can advise on risk and odds of an actual issue and they’d give you an honest assessment if an amnio is worth it. Your measurement seems to be not too large so you might just want the genetic counseling for peace of mind!

saral1717 · July 2019

@chichiphin I will take your advice and see a genetics counselor, thank you! It Seems like from your post that you had the NIPT done and for T18 it didn’t really show and increased risk and unfortunately that was the case for your child that they did indeed have T18? How alarming about the NIPT results! That was exactly what I was trying to find out and was what I was concerned about. Thank you for sharing your story.

chichiphin · July 2019

@saral1717 so the nuchal fold was larger than it should have been on the ultrasound. I then did the NIPT blood work and it showed a 1:5000 chance of T13 - which is not too concerning on its face. But the genetic counselor recalculated my chance with the knowledge of what was seen on ultrasound and it went to like 1:100 or something like that. The testing on the POC confirmed T13

saral1717 · July 2019

Wow ....

Nuchal Translucency

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