NIPT before combined NHS test?

[Colinthecaterpillar35]

Hi all

We want to be as informed as we can about our baby's health and would like, within reason, to have as many test done as possible.

I've been told by my midwife that my dating scan will be between 12-13 weeks and that the combined test will be done then. Am I able to have an NIPT test privately before my dating scan or can this only be done afterwards? We just really want to be aware of our circumstances as early as possible as I'm concerned my age (35) will play a big factor in the risks.

Any advice/experience greatly received.

Hi @Colinthecaterpillar35 I'm 41 and currently pregnant with my first baby. I opted for the Nipt test but waited till after my 12 week scan. I think you can do it from 8 weeks, but personally, following a previous miscarriage which I found out about at 11 weeks (the baby had stopped growing at about 8.5 weeks) I decided to wait as it is not the cheapest of tests. I had it on the same day as I had my combined test as knew I wanted the reassurance regardless. Both tests came back low risk. I had my nipt test at a local hospital which worked out a bit cheaper.

@Colinthecaterpillar35 I’m not sure about the area where you live, but currently it is being rolled out across the NHS that if you are high risk from combined NHS Screening, you would be eligible for NIPT on the NHS.

The above makes sense as NIPT is considerably more accurate when used within the context of a higher risk NHS Screening.

@SarahD19 this is only in some areas. In mine you only get offered an amnio or CVS if high risk. If you want NIPT you have to pay. I think this is due to change over the next year or so.

@Whoevenknows79 I know there has been a push for this to be embedded this year in particular. My area didn’t offer this when I was requiring the tests recently, but it has literally just changed in the last few weeks. This is why I’m suggesting it is worth looking into.

It is definitely worth looking in to. I'm in Wales and it was offered on the NHS here after my combined screening came out high risk.

The test is normally performed after the 10 week mark. You can find more info at www.arc-uk.org/tests-explained/non-invasive-prenatal-testing-nipt

Hi OP. We chose to have the NIPT test after our NHS ones came back as high risk. The only plus doing it this way round as they confirmed the baby was still alive about 1 minute before drawing blood. They very kindly pointed out they wouldn’t want to take our money if the baby wasn’t alive. Sounds negative but I’m grateful - you may not want to risk paying for the tests if there is a problem they will pick up at the 12/13 week scan or if for example the worst has happened. Hope that doesn’t sound too negative?

Thank you all for taking the time to comment and share your stories. I think we'll wait til after the 12 week scan now as it seems the most practical way - I'm just not good at all this waiting!!

Hey, we waited until after the 12 week scan as our trust do NIPT test for free if we got a high risk combined result, and we decided that even if it came back low risk we would still go for it but pay for it under the hospital (it’s cheaper and we didn’t want to go to one of those private scan clinics). We really wanted the continuity of care through the NHS this time too, and it helped that my scan was bang on 12 weeks and 0 days, so I didn’t feel we were waiting too long.

We decided on not having any private scans until the nhs 12 week one because of previous losses and false hope given by private clinics in the past.

Luckily we had a great 12 week scan this time and all the screening came back normal including the NIPT. It was the SAFE test through our hospital and I’d highly recommend it, it’s only a 5 day turnaround and the accuracy is 99% for all 3 trisomies. They don’t reveal the gender though for ethical reasons if don’t through the nhs.

I think if you’re 12 week scan is going to be a bit later I can see why you might want to have the NIPT sooner so you’re more informed earlier on xxx

*if going through the nhs

It depends on what you would do if there was a chromosomal abnormality I think. DH and I were confident we would terminate in that case and if we had to go that route, wanted to know asap.

NIPT is accurate from 10 weeks so result at 11 weeks. NHS pathway gives results from combined test around 13 weeks, then wait for NIPT and wait for results, takes you to 15 ish weeks. I felt that would be significantly worse as termination at that stage more complex- plus all the waiting.

But then it depends as well on how you feel about the cost of private NIPT as it's £400+.

It's important to keep in mind that NIPT isn't diagnostic; while it can give you an indication of the likelihood of an issue, you shouldn't base important decisions on the results without discussing with a medical professional. The accuracy of NIPT in non-high-risk or general populations is also less good, so it's important to consider that as well. That's one of the reasons why NHS services tend to only offer it (free of charge) to people in higher-risk groups, as those are the groups in which it can be most helpful.

A 'low probability' result is usually reassuring but can't be guaranteed. A 'higher probability' result doesn't mean a baby definitely has a problem - it can, however, help people with making decisions about whether or not to get diagnostic tests.

Always make sure you can discuss results with a clinician who has access to all of your relevant medical information.

Good luck with your pregnancy ❤️

Yes. I am 34, had Panorama privately at 10+6, results came back before my NHS 12 week scan and combined test. I was very happy with it. As pps said, it's around £400. Do your research as different NIPT tests have different predictive values, read up in advance. Good luck. xx

And you can do some NIPT tests from 9 weeks, some from 10. They say the wait is 2 weeks, but mine were back aftr just over a week. I personally wouldn't bother with it after the combined test if all is well, I did this to know if my son was ok after 3 MCs in a row, so the sooner the better. But it's your personal choice. xx

@Colinthecaterpillar35 good luck with everything! Although just as @Scirocco has said, generally the NIPT test is less helpful in the event of lower risk NHS Screening.

Also be sure to distinguish detection and sensitivity rates from positive predictive value. Many people use these phrases interchangeably, but no NIPT is anywhere near 99% accurate in terms of positive predictive value. I know people with doctorates who have been misled and thought a positive result was 99% accurate and in fact these particular results, in that context, NIPT is less than 40% accurate.

This is a serious issue which has been flagged up a lot but is still seemingly little understood. www.asa.org.uk/news/non-invasive-prenatal-testing-nipt-a-look-at-the-asa-s-rulings.html

Hi @SarahD19 according to the SAFE test website it’s 98-99% accurate for both PPV and NPV:

www.stgeorges.nhs.uk/wp-content/uploads/2020/03/safe_test_NHS-03-20.pdf

www.natera.com/womens-health/panorama-nipt-prenatal-screening/

Here is the info regarding Panorama NIPT xx

@Cafeaulait27 I suspect this would fall under the misrepresentation of statistics which has been flagged up. It is impossible for PPV to be that high on NIPT. For more information may be worth having a full read of Nuffield’s full review of these concerns. Multiple NIPT are advertising in this way but it is wrong and misleading. Honestly I know people with PHDs etc who have had these tests and believed this sort of information and struggled to challenge it.

www.nuffieldbioethics.org/wp-content/uploads/NIPT-ethical-issues-full-report.pdf

Personally I would be tempted to decline (or at least put in a complaint) in regards to the SAFE test on that advert alone - due to the clear ethical implications of promoting misinformation and that the NHS would endorse this - but it is personal choice. As I’ve stated previously, this misinformation and not understanding how NIPT works is normalised even across professionals. I feel strongly that services should be more accountable.

Even CVS does not have this level of accuracy and that is an actual biopsy of the placenta (which may or may not match Fetal chromosomes). NIPT is guess work of trying to establish cell free DNA which comes from the placenta. No cells come directly from baby.

Issues such as maternal health conditions, maternal mosaicism, vanishing twin, confined placental mosaicism may all invalidate, or at least complicate these tests. This is why it is statistically impossible for NIPT to legitimately claim accuracy in the general population above 80% for the most part - in terms of Positive Predictive Value (PPV).

Negative results and NPV by definition are much easier to achieve. The majority of these conditions are less prevalent than 1% of the population. Trisomy 13 and 18 less than 1/1000. Hence even if there was no science, and a negative result claimed for everyone, over 99% accuracy or even 99.9% accuracy in terms of NPV could basically be claimed. It is all about how statistics are explained and presented.

@PurplePansy05 this NIPT looks more legitimate in terms of the advertising for what it’s worth. Some of the PPVs look slightly high (at 90% mark), but this is achievable with NIPT when used in targeted populations such as higher risk subgroups.

@SarahD19 so are you saying that you believe the 99% PPV and NPV for the 3 trisomies are false advertising?

Not having a go, just interested, as I didn’t think this would be possible, especially in something the NHS use and the hospital that does it (st georges) is an nhs hospital.

I’m very interested in this as I was originally put off NIPT as I looked at harmony and panorama and their stats didn’t look great. When I looked at the SAFE test and the stats looked much better and our hospital do it, we decided to go for the extra piece of mind. (Obviously understanding it’s still a screening and only covers 3 trisomies).

@Cafeaulait27 my interpretation of that information is that the PPV given is pretty much impossible for a test of this nature (I have now raised this as a concern with the appropriate body in light of ASA rulings). The NPV is likely accurate. But all I would suggest is to look at figures like NPV with a critical eye - in terms of how statistics can be presented and interpreted.

My post is not to alarm. A negative result from NIPT is more accurate than a low risk NHS result for instance despite limitations. As such, the test has a place and should provide reassurance to many. NIPT figures will vary slightly for tests and change for sub groups. But any NIPT that claims PPVs that are far off 80% for Downs, 37% for Edwards or 49% for Pataus across the whole population, should raise legitimate suspicion. As I’ve said, accuracy can improve with higher risk sub groups so this isn’t a blanket rule.

I find this resource quite scathing in that it doesn’t explain the benefits of NIPT from increased accuracy for risk assessment. However it does raise very valid points that are often overlooked in respect to NIPT www.dsrf-uk.org/nipt-facts/

We have seen that as we now have an older demographic having babies, NIPT can be a very useful resource that compliments the NHS combined screening for refining risk assessment (the NHS calculates using age so brings up more high risk results with older mothers). However limitations of NIPT are rarely understood/talked about. I guess ultimately everyone wants reassurance and grey areas rarely add to feeling reassured.

@SarahD19 yes I agree. It is quite difficult to get correct and easy to understand information on how accurate it is, and that’s all people want - people want to know the facts about accuracy when they are having this test, particularly when paying large amounts for it.

For me it was the NPV over 99% that made me want to have it. As we already had a low risk combined result, I knew that a low chance NIPT result would be 99% accurate and therefore be reassuring.

I was pretty scared about having it - because I was worried if it came back high chance we might end up doing an invasive test unnecessarily (even though I know a miscarriage from this is very rare, it just would’ve been very confusing to get a low combined screening and high NIPT). But luckily it all worked out and we got low for both xx

@Cafeaulait27 and that’s where the NIPT excels. It can provide increased reassurance with low risk results. I’m really glad you’ve had a positive experience with it.

I also think it is worth highlighting for anyone reading this that there is a lot of research which suggests miscarriage risk is overstated for invasive testing obgyn.onlinelibrary.wiley.com/doi/10.1002/uog.20353

I know from experience there can be a lot of anxiety and guilt involved with having to make these choices so believe everyone should be informed. They are not nice tests to have - but equally if anyone can feel reassured by more recent evidence around miscarriage risk being much lower for invasive tests, then that is a positive.

Well if it was "NPV that made you have it" then Panorama is better than SAFE in that regard, and I believe Harmony might be too or at least it's very comparable. I don't see how you can say at the same time that you were "originally put off NIPT as I looked at harmony and panorama and their stats didn’t look great". 99.99% NPV looks better than SAFE, were you actually looking at PPV then? Because as pp says, there is not an NIPT test able to have PPV you're referring to as it stands.