prenatal test or amniocentesis?

[doga1974]

Hi,
I am pregnant at 40 and have a history of miscarriage because of trisomy 4, so amniocentesis seems inevitable. But I just learned that there is a new blood test (harmony)that gives accurate results ( but my obgyn says not as accurate as amnio) Trying to conceive for 2 years so I am reluctant to take the risk of amniocentesis. Is there anybody in the same situation or have an opinion about this new test? They say amnio has %100 reliability, but in the reports I saw it says this analysis can't find mosaicisms and rare disorders etc. , so it looks like amnio is not %100 either.

I'm having the Harmony. It only tests for Down's Edward's and Patau's though. There is a leaflet on the website of the company that developed the test. The Fetal Medical Centre does a package that includes a scan alongside the test, so I am having that. It seems to be the best of both worlds for most of the common chromosomal abnormalitites. Although I am not sure that it would cover trisomy 4.

trisomy 4 is not important because it is so serious that these babies can never survive even the second trimester. But once you have a pregnancy with chromosomal abnormality with older age, they label you high risk. For down especially, is it reallt inferior to amniocentesis? And what is your age?

I'm 38.

The leaflet I mentioned gives you the accuracy rates for each of the trisomies it tests for. I think it's 98% for Down's. A bit lower for the other 2. The only way to know 100% is to have an amnio, but I have decided that I wouldn't take that chance. It has taken me more than 3 years and 4 rounds of IVF to achieve this pregnancy. So the Harmony is right for me. It'll give a greater degree of accuracy than th NHSe triple test without the risks of an amnio.

How I wish none of these tests were discovered :( pregnancy is full of anxiety now. in fact we can control a little, I know, there are syndromes that can't be diagnosed before your son/daughter is 20 or impossible to diagnose like autism before birth but still we feel like we have to eliminate every risk possible...

Is a cvs test an option? I know it has a risk too but it's earlier than the amino.

cvs has a considerably higher miscarriage risk than amnio.

This is the Harmony test leaflet I mentioned, in case you are interested.

Harmony is over 99% accurate for T21, less so for T13 and T18. It's so close to the accuracy of CVS/amnio that doctors (well, the ones I've seen who contributed to a lot of the research, so I trust them!) consider it as conclusive for a negative/low risk result as CVS/amnio.

There's less accuracy with a positive result but they're very rare and most people would go for an amnio in those circumstances.

Technically it's not as accurate, but in reality it's splitting hairs, especially compared to the NT screening.

Have a look here: www.ariosadx.com/review-clinical-data/clinical-data/

I second having the Harmony at the FMC anyway. They really are the experts in diagnosis. My Harmony results gave something like a less than 10,000 chance of the trisonomies tested for. With amnio the risks are hugely reduced by the experience of the Dr. On the NHS they told me that I had no say over this and someone relatively inexperienced could possibly end up doing it so I had Prof. Nicolaides do it at the FMC (and while not a pleasant procedure) but everything was fine.

Hi Doga,

Sorry to hear about your history. Pregnancy is stressful enough.
I just wanted to check uv thought about the necessity of any test rather than just between the two?
These are just diagnostic tests. They don't give any information that can result in helping your baby in any way, but some of them do pose a risk.
My personal opinion is that they are recommended/offered way to much here.

In the case of trisomy 4, which seems to be your personal issue, this will lead to miscarriage anyway so doing any test is not going to change a thing.
I realise that with this history (and your age) you are probably at "high risk" of other chromosomal abnormalities, but I think before you consider the tests you should consider your response to the results you may get.
In the case of any abnormality that is going to lead to you losing the baby, the tests are completely irrelevant (except maybe time).
The only way they are useful is if you get a positive for something (like Downs) where your baby will survive, but your CHOICE would be to have a termination. This choice is completely personal and only you and your partner can have a say, but unless you have already decided that this choice is yes then ANY risk to your pregnancy I would feel is too high.

I'm sure you've thought of all this (and I'm sorry if the wording of this was upsetting), but I think the doctors seem obsessed in testing to find out what they can - but sometimes the finding out isn't going to change anything. Also, as the other poster said there are 1000's of problems that we don't focus on during our pregnancy simply because a test is not offered/available.

So my twopence would be do the Harmony - you get (slightly) less accuracy, but with no risk to a hopefully healthy baby. U get some piece of mind if you get a negative result and you have less of an argument with a doctor that wants a box ticked. (and if you get a positive you can always get the amnio IF you think the result will be useful to you)

Good luck with your pregnancy.
Hope everything goes well for you
xx

I also wanted to mention ARC, a wonderful charity who can advise on antenatal tests and choices. They were amazing when I faced some difficult decisions.

I had Panorama (like Harmony). Was lucky and had a good result, so put my mind at rest nice and early (you can have it from 9 weeks).

thanks for all comments, I could not access my computer so I could not answer for a long time. I have to make a decision now between amnio and harmony test. I have a few weeks to decide. The problem is , the reliability ratios that the prenatal tests offer are not accepted by some of the doctors which makes it difficult for us to decide. today, the perinatologist said that there is over %10 risk of false results in prenatal tests( and the ratios companies present are misleading ) and that we should choose amnio or cvs (preferably) In fact, the amnio performed by a perinatologist costs as much as prenatal test so one cannot be sure that these doctors are saying that because of conflict of interest. if these prenatal tests become routine, they will lose a lot of money...

cvs has a considerably higher miscarriage risk than amnio.

What is your understanding of the relative risk?

I ask because while CVS is often given the higher risk of the two, I wouldn't say it was considerably higher.

in many references , it says that cvs is about two to four times risky than amnio, ( for example here :www.babycentre.co.uk/a328/chorionic-villus-sampling-cvs) this is also what we are told by multiple experts. it is both a more complicated and difficult procedure and performed earlier in pregnancy ( when the risk of miscarriage is higher), so perhaps these are the reasons why. however if the perinatolog is an expert with a lot of experience, maybe the risks can be equated. but for me, at least 2 times risky means considerably riskier. of course, everyone makes the best personal decision.

one more detail about cvs is if mosaicism is found in cvs, it may not mean that the baby has it so they recommend to confirm the diagnosis with amnio since it doesn't produce false results. if this is the case, you have to go through the risky procedures twice.

The risk with CVS or amnio is in part to do with the experience of the person doing it. I had mine done by Prof. Nicolaides at the FMC as he is super experienced so this is a route you could consider. When I asked my NHS consultant if someone experienced/senior could do it he told me I had no choice in the matter and yes, it could be a relatively inexperienced Dr.

Yes, exactly - so much depends on who does the test and you really don't get a choice with the NHS. I would recommend the professor as well.

There are a lot (relatively speaking) of false positives with the prenatal tests, but not many false negatives, barely any in fact. Down Syndrome is also a lot more reliable as a result than most of the other trisomies too. So if you got a negative result and were only concerned about Down Syndrome you could almost certainly feel reassured. And with a clear scan you definitely could be - the other trisomies are nearly always visible on ultrasound with soft/hard markers by 12 weeks.

I think the only way to confirm or rule out trisomy 4 would be an amnio...

There is a huge amount of confusion around the difference between screening tests and diagnostic tests- harmony and Nuchal Translucency are screening tests- not a diagnostic tests so could never give a definitive yes or no...... only a risk.
Amnio and CVS are diagnostic
I am 41 and pregnant. With my last pregnancy(age 37) I had a 1 in 4 risk of Down syndrome and Edwards and Patau both single figures and had a CVS. This time I am booked for a Harmony test as I am pretty much guaranteed at my age to get a very high risk Nuchal screening result and be recommended a CVS. The Harmony test on the other hand does not take age into account when calculating the risk so I will have as good a chance as anyone of getting a low risk result. I wonder if the Harmony is worth thinking about from an age perspective rather than a medical history point of view.

The miscarriage risk from CVS or Amnio is operator dependant- so your consultant should be able to tell you their own miscarriage rate and how this compares to the average of their peers. My (very experienced) Obsterician had a zero miscarriage rate.
Good luck whatever you decide and fingers crossed the outcome is good

thank you for your contributions. at 13 week scan and doppler today , no soft/hardmarkers no anomalies, nt is good, 1.1 at 12th week, 1.6 at 13th week. rightsaidfred, how did your previous cvs result with such a high risk ratio? I think some doctors prefer cvs because if there is a major anomaly and you decide to terminate the pregnancy, it is hard after 13th week, your choices are to deliver the baby or choose c-section, which makes the situation more difficult...

amnio gives you certainty. I couldn't be asked to play with statistics any more. Amnio is good.

Nifty is also worth looking at. High accuracy, no risk.

Nifty is also a screening test- so can't be 'accurate'..... just gives a risk

CVS result was good in that there was no chromosomal abnormality. But then they decided that if there wasn't a chromosome problem then there must be something else so I was scanned by the consultant weekly and had foetal cardiac echo and kidney scans...... then at 28 weeks they decided everything was normal and he was. He's a strapping, gorgeous 3 year old now :-)
Doga- Your nuchal fold measurement looks good. Did you get a risk result or just leave it at that?

rightsaidfred, I am glad your story has a happy ending :) I hope everything goes well for your new baby , too.
they calculated my combined risk for t21 as 1:42, for t18 and t13 less than 1:90000. so for me the risky one is t21. however, my perinatologist thinks I have risks for many other chromosomal abnormalities not even mentioned ( including turner syndrome and some syndromes I never heard of) because of my age and previous miscarriage because of trisomy 4 mosaicism. He insists that I should prefer invasive tests.

unbelievable but I just learned that they miscalculated my risk! despite there is no indication of the absence of nasal bone ( they never asked if my baby had one), they accepted that my baby has no nasal bone and since he has a nasal bone, now they recalculated my risk of 1: 42 as 1: 3500! despite my age, doctors now say that I may skip amnio. what's more, now it seems more possible what the genetic counselor said before: trisomy 4 mosaicism that they found as the cause of my previous miscarriage can also be a lab error, he said that in culturing cells, this may happen sometimes. ( because of something like contamination )