Dr Nyberg, when you get a report for a non-invasive prenatal test, what does that show?
When you get a result back for the NIPT test of course it's usually normal.
The important thing to remember is that it's normal for the chromosomes that were tested
for.
So if you choose the Harmony test, if a patient chooses Harmony test, it's normal for Trisomy
21, 18 and 13.
That is there's a very low risk of those chromosome abnormalities.
It doesn't mean that all the chromosomes are normal because it didn't test for all the
chromosomes.
Now the results can come back in 2 different ways.
The Harmony test for example will come back with a risk, a very low risk of 1 in 10,000
and sometimes that confuses patients.
That's the lab's way of saying it's normal.
It's as low a risk as they can get, but they don't want to say it's like saying it's not
100%, but they use that for all patients 1 in 10,000.
Other labs like Sequenom or the MaterniT21 will come back with a positive or negative
report.
But again, most times we're going to get a normal report and we're very happy to tell
patients that it's normal, but it's important to recognise that it's normal for the chromosomes
that it was tested for.
If it's positive, then we would need to confirm that.
Fortunately that doesn't happen very often, but certainly if it's positive there's a much
higher risk of a chromosome abnormality and usually we'll know that also in combination
with our ultrasound.
But anyway we can discuss that with the patient if that were to occur, but it does not mean
100% that it's an affected baby.
So, if you get a positive report for a patient, what happens next?
Where do they go from there?
Well, it's individual.
If we get a positive obviously I'm going to discuss it with the patient and we're going
to correlate that with any ultrasound that we might have done here.
If it really does have, if there really is an effected baby then we will have clues from
the ultrasound.
But then we'll give them the option or recommend that they have other kinds of testing to confirm
that and that's available and we'll get the patients to a great resource.
And further testing would be the more invasive type of testing by CVS or amnio.
Is that correct?
That's correct.
That's a good question because you could do either test, but because the NIPT test is
actually very similar to a chorionic villus sampling, that is the cells that we test for
really seem to come from the placenta that's true of CVS as well.
We actually would recommend the patient wait and have an amniocentesis if they have a positive
NIPT test.
An amniocentesis isn't performed until after about 15 weeks.
So if they did have a positive result, and again that's uncommon, we would ask for confirmation
with an amniocentesis after 15 weeks.
And if you get a negative report does it mean that everything is fine?
Again, if you get a normal result it's normal, or very likely to be normal, we can have a
high confidence it is normal for the chromosomes that were tested.
But not for chromosomes it didn't test for.
And also not for what I'd call structural defects.
For example, some patients are under the misconception that if it's normal it means that the baby's
entirely normal.
Again it's normal for the chromosomes, but conditions like heart defects usually have
normal chromosomes and they're actually more common than some of the chromosome abnormalities,
or many of them.
So that would not be picked up by the NIPT test.
We would need ultrasound to do that, which is why, just as an example, why the blood
test and ultrasound work so well together.
The blood tests are very helpful, but the ultrasound is also extremely helpful.
So the blood test is not the whole picture, it's part of the picture.
It's part of the picture, that's right.
It's just like if you had a test for example for diabetes during the pregnancy, it would
show you don't have diabetes, but it doesn't show you don't have hypertension or something
like that.
It only tells you what it tested for.
Dr Nyberg, thank you very much.