Should i still have the triple test if i have had a nuchal scan?

[misselliemae]

I am 14 weeks pregnant and had a private nuchal scan 2 weeks ago - results were fine. My midwife said in passing that i shouldn't now need a triple test, but didn't really explain why, and i don't have an appointment until 20 weeks. Confused as to what a triple test tests for, does it test for the same things as a nuchal scan or does it test for additional things? Am worried that i am misssing out on a test that i need to have. Thanks v much.

In my opinion, no.
Triple test tests for the same thing as nuchal scan. I don't see why you'd want to do a test twice...

The nuchal is more accurate than the triple.

I think that there is also a technical reason why people shouldnt have the nuchal and then the triple. Something to do with the fact that the odds of the triple are calculated on a population of women who didnt have nuchal scans ie if your nuchal had been really bad then you might not now be considering the triple, because you would instead be going for definitive testing. The fact that nuchal scanning selects out a number of affected pregnancies then changes the accuracy of the triple test.

I'm not sure if I have explained that terribly well. Hopefully someone else can do better!

I'm interested to know about this, too.

I thought that the triple test was called that as it tests for the three chromosomal disorders that the nuchal/nuchal+bloods looks for. So - my understanding, may well be wrong - if you have a nuchal test you don't need the triple test as it is the same thing.

When I told my MW I was planning to have a private nuchal scan + blood tests, she said the NHS would not do blood tests at 16 weeks or whenever, as they 'wouldn't be accurate'. However even given monkey's explanation, I don't understand, surely the tests are independent. Eg what if I didn't tell my MW I had the earlier tests?

I guess it's academic in my case as I was lucky enough to have really good results from my nuchal + bloods and I don't see the need to go for another test. But I'm still interested to know the answer! Am seeing MW next week, may ask her again.

The two tests look for different things. Both offer a way of seeing if the baby is at increased risk of certain conditions, but the way they go about it is different.

This might be of interest (despite what I said earlier about people not being meant to have both!):

link

Thanks monkey that's interesting. So from what I understand from the abstract, there is not a great degree of correllation between the results of the two tests, but if both were negative (or both positive) it would add weight to the results. So for most people, it would be best not to have both tests because the numbers they get out would likely be different, which would only lead to extra worry.

I suppose it depends on how worried you are by the chance of a false high risk result. They said that detection was improved by having both tests, but like you say, that will be at the expense of more people getting high risk results than they would if only one method was employed.
I suppose there is a limit to what conclusions you can come to from an abstract!