Advice please for Nuchal fold and NIPT

[ealexia]

So I have a few concerns and feeling incredibly anxious. I’m sorry this may be long!
At my 12 weeks scan I had a Nuchal Translucency of 3.3mm which is considered within normal range (anything over 3.5mm is referred to specialists). For me this felt high still, I had the combined screening and I got low risk back. However, my risk for Down syndrome was 1-380. I panicked and wondered how this could possibly be low risk. I was told my bloods were fine it was just the nt that made this number like this.

Fast forward to 20 week scan they measured the Nuchal fold at 6.3mm. This time being just over the threshold of 6mm. I was referred to Fetal Medicine unit which confirmed the same measurement. They told me everything else appears normal apart from this measurement. I was given the option of amnio but I decided to go for NIPT because of the small risk amnio carried.
I am freaking out, possibly irrationally, waiting for these results. I’m now on day 12 and still no news. They said within two weeks but I am so anxious!!
I just want to know if anyone has been in this situation. And is it possible for the combined nhs to say low risk but then the NIPT to come back high risk ? I can’t stop over analysing!

Any advice would be appreciated. Thank you

My advice would be to chase it up. Private NIPT results take 5 days. The results are very accurate. I think no news is good news. Thinking of you x Please let us know how you get on. I have my 12 week scan tomorrow.

Hi there how did you go? My situation is the opposite I have a High Risk NT and Low Risk NIPT so have no idea what to think. I hope everything worked out well for you xx

Hey, NIPT results also came back low risk. I feel like I can relax a little now and actually start to attempt to enjoy the remainder of my pregnancy. Will have another scan at 28 weeks just to check baby over. Feel optimistic!
How are you feeling ?

Hiya, great news!! What a relief!!

Did they tell you the gender when they gave you the NIPT result as I know they can tell from this test...?

I already knew the gender from the 20 week scan as I did the NIPT afterwards. This particular NIPT doesn't reveal gender but I know that other ones such as harmony do!

Excellent. You can enjoy your pregnancy now

Hi this is the exact same that happened to me. I spent my whole pregnancy from 20 week scan worrying. We was told at 12 weeks we were low risk and then at the 20 week scan we were told about him having a nuchal fold. We was sent for another scan the day later where they got the measurement of 6.5mm and said it's over the threshold of what they like to see. They offered us the amniocentesis which we declined due to the chance of miscarriage and we were told we could pay for a private blood test for £400. We declined that to. She then offered us a termination. I couldn't believe it. Panic set in! But I just had in my head I was having this baby no matter what and everything is just a chance of the baby having something. So we got discharged from the PFU clinic and just carried on as if it was a normal pregnancy.
Luckily he arrived healthy and no signs of any chromosomal abnormalities
Just gutted I worried so much and it spoilt my pregnancy.

Statistically NIPT for Downs has an ok accuracy rate (80%) but it is VERY VERY far removed from diagnostic and I certainly would not rely on it.

NIPTs have been criticised by ethics committees and watchdogs recently as they mislead by claiming to be “99% accurate” when their baseline actually is more around 50% predictive values - with accuracy for some conditions being only 30%.

www.asa.org.uk/news/non-invasive-prenatal-testing-nipt-a-look-at-the-asa-s-rulings.html

www.itv.com/news/2019-11-20/ads-for-three-prenatal-genetic-test-firms-banned-for-using-misleading-statistics/

My understanding from those articles is that the issue with the reported accuracy figures is the discrepancy is between the “detection rate” and the “positive predictive value” of the NIPT. In other words, 99% of affected pregnancies receive a positive result for Down’s Syndrome but (often much) fewer than 99% of pregnancies which receive a positive result are in fact affected- false negatives are rare but false positives are more common.

So, the 99% detection rate figure for Down’s Syndrome indicates a 1% false negative. So although the NIPT is not diagnostic and a positive result would need to be confirmed by an invasive test, a negative result for Down’s syndrome is very accurate and generally no further tests would be indicated to confirm this further.

This applies to Down’s syndrome only, the NIPT is much less accurate in detecting other chromosomal abnormalities.

@MajorFaffington you need to re-read. It is a manipulation of statistics. You are right in distinguishing PPV and false detection but have missed the meaning and implications completely.

Yes as I have noted in all my comments, it is MORE accurate at detecting Downs (80% accuracy). However the “99% accuracy” is basically their working backwards and saying “in many instances our detections tally with other tests”. However it ignores how many positive tests etc they actually have and actual detection rates within the population. So this figure tells you nothing about their detection rate - and knows consumers will perceive it as 99% from this statistic.

Additionally it works on the basis that many conditions (e. g. Edwards and Pataus) impact 1 in maybe 5000 etc. Hence even if there wad a dummy figure and they gave everyone “all clear” results, they would still accurately predict more than 99% because less than 1% of the target population are impacted.

Reading through these threads and the people who STILL get confused and advocate for NIPT just proves how unethical the promotion of these tests are.

The only part of your comment that is relevant is that false positives are more common. However I was sharing my post for the person who initially was anxious about a high risk NIPT. If you are concerned about a high risk test result, my advice to anyone would be avoid NIPT given how many false positives there are and how much unnecessary trauma and termination the depraved, unethical promotion of these tests has caused.

I have reread the articles and I am confident that my understanding of the accuracy of a low risk NIPT result is correct. I did a lot of research about this following a high risk combined screening result and a low risk NIPT result in my recent pregnancy.

“In these three rulings against Ultrasound Direct, My Baby Enterprise and The Birth Company, each provider was judged to have misled consumers by quoting 99% “detection rates”. These detection rate figures represented the proportion of foetuses that the NIPT test correctly identified to have a condition such as Down’s syndrome, out of a base of all foetuses that actually had the condition.

Although ‘detection rates’ are real statistics used by medical professionals that provide genuine insights, and although all the figures quoted were accurate, the ASA considered that their use on these websites, without an accompanying explanation, were likely to mislead consumers materially. The ASA considered that consumers would understand the ‘detection rate’ to represent the likelihood that a foetus would have the genetic condition, if they received a positive result. For example, the claim “Accuracy in Detecting Down’s Syndrome” of “>99” would be understood to mean that there was a 99% chance that their foetus would have the condition following a positive NIPT result.”

I can’t see any suggestion that 99% accuracy for “detection rate”- a negative result- is not correct.

OP on this thread hadn’t received a high risk NIPT result- she received a low risk NIPT result after an elevated NT result. You told her not to rely on the NIPT result, but I was reassuring her that negative NIPT result for Down’s syndrome is considered very accurate.

I’m sorry that you had a difficult experience with a high risk NIPT result, and I can absolutely see that the test has limitations. But the NIPT has a very important role in providing reassurance for women, like me, who receive a high risk combined screening result and are then able to receive 99% accurate confirmation that their baby is not affected by Down’s Syndrome without risking miscarriage with an invasive test.

I don’t know about private providers but it was made very clear to me within the NHS (and other posters report the same) that a NIPT is not diagnostic and CVS/Amnio would absolutely need to be carried out to confirm a positive result. I really don’t think women are commonly being encouraged to terminate based solely on a high risk NIPT result, and i’m so sorry if this was your experience.

@MajorFaffington the original comments on this post have been around having NIPT as though equivocal to diagnostic tests to put mind at ease.

I have seen this on countless threads and people discussing termination on the basis of these results very much seeing the tests as diagnostic.

Whilst the following is true:

• NIPT has greater positive predictive value (ppv) for Downs than any other test, it is still only 80%.
• False negatives are indeed rarer with many NIPT tests. This is exactly why I’m saying choosing to take NIPT in early pregnancy prior to it being possible to diagnose is not appropriate to put a person’s mind at ease. A person could realistically get a high risk result then have 2-3 months of waiting to get a diagnostic result and are often obvious to this - is this ethical in your opinion?

This OP got lucky with a low risk result for a condition in this instance - and indeed many jump on the bandwagon and tell people on these situations to take NIPT. My post is to inform and make people aware that leaping in to take NIPT as though diagnostic to help anxiety is profoundly dangerous.

CORRECTION

*NIPT has a greater ppv for Downs than any other condition (not test). That is due to 80% ppv as opposed to NIPT only having 30-40% ppv in some instances

And also I haven’t had NIPT so please do not make such assumptions. But I do know that actual diagnostic tests are complicated enough (mine has already been a 4 month process) and NIPT adds another two months or so for many.

You sound a rarity of being informed. Many people have spoken to me about being pressured to terminate on the basis of NIPT alone and being told it is 99% accurate. In fact the profound lack of understanding demonstrated on the majority of these threads proves that.

Whilst it is technically correct a negative result may be 99% accurate, that is very misleading to cite for the reasons I have already stated in my above comment.

The purpose of these tests is to assess risk FOR conditions, not risk of not having. In cases with many trisomies you can already assess through basic maths that it may be 99% likely baby is healthy - even some “high risk” triple screening results are only 1%.

Why do a test that only averages 50% positive detection? Might as well flip a coin and save the money and stress. At least the odds there are transparent...

I think we will have to agree to disagree with regards to what the statistics mean, and the value of the NIPT. OP and I have only ever been discussing NIPT following high risk combined screening/elevated NT, so i’m not sure of the relevance of early testing and having to wait months for a diagnostic test.

My reason for commenting was that OP has said, following a very worrying time, that she’s relaxing and feeling optimistic about her pregnancy following her NIPT result. The last thing she needs to hear is that she can’t rely on the NIPT or that she ”got lucky with a low risk result”.

@MajorFaffington

It seems to me that you are taking what has been said out of context because you are focussed on your own agenda.

My point is that despite numerous comments promoting Harmony etc and it’s accuracy, it is misinformed to claim it holds diagnostic validity or accuracy.

Ultimately a lot of people, statistically do essentially get lucky and are reassured then use the test again and promote it. The collateral damage is that people end up further misinformed and I know of numerous instances where people have literally terminated what, in all probability, may have been a healthy pregnancy because of these tests. Distraught does not cover it for such individuals.

Essentially OP was in a heightened state of anxiety about a risk of less than 0.30% likelihood of Downs Syndrome. If this was enough to cause distress, I do think it is irresponsible if she was not informed that actually, the nearest a Harmony test or similar NIPT test could do would be “reassure” by tripling that risk to maybe 1%.

Likewise an actual reality for many is having NIPT and being told that their baby is high risk for conditions incompatible with life. To receive such a “diagnosis“, I think many would agree, would be more traumatic than being told your baby has a 0.3% risk of Downs. And this anxiety, then learning that on top of such a prognosis there will be a MINIMUM of a two month diagnostic process to follow (sometimes many more months on top) - is a dilemma that is being promoted and normalised through NIPT.

I understand NIPT may have uses within the context of gaining further assessments in high risk situations - and managing this risk. But to promote this test within routine practice is dangerous imho.

Unless OP was fully aware of all of the above - and all commenters alluding to NIPT being a source of reassurance from 9 weeks gestation were also aware, then there has not been appropriate counselling imho.

NIPT has no diagnostic capacity as a test and is an assessment of risk factors restricted to a very limited set of conditions. An “all clear” cannot guarantee a healthy pregnancy, and an “abnormal” result cannot diagnose anything. Parents-to-be sometimes think as they (often) pay privately for these tests, they are more accurate/better than what the NHS can offer.

There is a reason an anomaly scan occurs at 20 weeks gestation - because before then foetal anomalies can rarely be accurately assessed, recognised chromosomal/genetic conditions or not. Even actual diagnostic prenatal tests (e. g. CVS and amniocentesis) are extremely limited, as I have experienced first hand.

The science behind NIPT is exciting and new - but it isn’t complete and it is NOT diagnostic. NIPT definitely has a place within the context of assessing and managing risk, but currently no more than this. It scares me how these tests have been interpreted and promoted. So many people are being misled, seemingly due to providers putting money before ethics. It is a dangerous misrepresentation of science; inadvertently inflicting emotional torture upon vulnerable parents-to-be at best - and outright dishonesty/exploitation for financial gain at worst.

People are (wrongly) being told at two months pregnant that their baby could die or have significant disabilities. Some choose to terminate either due to misinformation and interpreting NIPT as diagnostic - or feeling emotionally unable to manage the uncertainty of maybe 2-3 months of ongoing diagnostic/screening tests waiting to find out if their baby will survive. Or a combination of both factors. My post is not to judge parents who face this dilemma, but to try to minimise parents-to-be being placed in such a tenuous and vulnerable position to begin with.

Hi guys,
I only wanted to quickly chime in because I think you might be both kind of arguing some of the same points without realizing it? I have also been horrified by the use of the "accuracy" statistic of Nipt as in some cases that's almost meaningless to an individual patient. As pointed out by everyone, positive predictive value is the number we need here when a "screen positive", is found and that is NOT made clear to....most people I would say.
But I did want to further reassure the OP about the value of an Nipt when a negative result is found. The negative predictive value for Down syndrome is much higher than 99% actually, according to what I've read. Meaning false negatives are pretty rare. I just googled out of curiosity and found a calculator, where, a negative result for Down syndrome on an NIPT at my age (36) has a 99.9965927941856% chance of being correct.
www.perinatalquality.org/Vendors/NSGC/NIPT/

So OP, you should feel reassured by your Nipt results. But also, SarahD, as I said on another thread, i'm also horrified by the marketing around these tests. :-)

I’m sorry OP that your thread has been derailed with discussions about NIPT screening that aren’t relevant to your situation. It is correct and proper that you are reassured by your result and I wish you the very best for the rest of your pregnancy.

@georgiablue2 Cross posted-this is obviously relevant and exactly what I have been trying to reassure OP of.

@georgiablue2 thank you!

My original comment was not about disputing that a negative result has accuracy and actually it is helpful to know that the negative result for Downs can have over 99% accurate as the various sources I have read simply cite anything around the 99% mark depending on the specific NIPT.

My comment was in response to NIPT being compared to a diagnostic test, being described as “accurate” and being normalised within discussions. As you have said and I reiterated numerous times, a test for screening which has such a low PPV is very misleading and causes harm.

Whilst I am thrilled OP and @MajorFaffington got good news in this instance, to me this does not justify colluding with a damaging narrative that has destroyed so many lives and caused people to terminate healthy pregnancies. I will continue to speak out to raise awareness, knowing that doing so may help someone else reading this who may not have such good fortune. As I’ve said, it is a statistical lottery and I would not wish drawing the short straw on my worst enemy.