Need input about chromosomal/genetic screening tests. A bit long, sorry.

cookie2279

Hi everyone.  I need your expertise!

 I live in India due to my husband's job, and I receive my prenatal care collaboratively with both an indian OB and the health center for expats, which is staffed by generalist MDs and NPs.  Well, yesterday I had my first prenatal appt at the health center.  I declined the optional first trimester "double marker test" which, to my understanding based on what my OB told me, only tests for trisomies (Downs, basically).  We don't want to know our risk for chromosomal problems because it wouldn't change anything, and I'm a worrier--if we came out high risk, I would spend the rest of my pregnancy worried for baby--not good.  

 Here's my dilemma:   

The health center NP told me that the blood tests that go along with the NT scan (which I did have--long story--but everything was fine) ALSO test for other things like neural tube defects/spina bifida, which can be corrected in utero, before baby is born, so she encouraged me to reconsider.  I was totally confused because I was pretty sure that the blood work for neural tube defects was done in 2nd tri and still just gives you your chance of having a problem--that you need follow up amnio and high resolution ultrasounds to diagnose.  

 Can anyone clarify this for me?  

We were planning on declining the triple/quad tests too, for the same reason, but if we are missing out on finding out something about baby that we can actually do something to improve before baby is born, then I would want to know that.  Agh.  So many decisions.  

 Thanks in advance.  

brwneydtexasgal

No input, but Im glad to see another bumpie that is overseas! We are in the UK until 2014 (DH is military), how are you liking India? and sorry that your having problems with your doctor.

alliapistor

I did the NT scan and first trimester bloodwork and it only looked for Down Syndrome and Trisomy 13 and 18.  The genetic counsel said that I needed to have bloodwork done at 16 weeks to check for neural tube defects, including spina bifida.  I think that is called AFP testing.  So you are correct, that it is a different blood test than the first trimester screening.

Fisherman'sWife

I am pretty sure there is different bloodwork for the second trimester screening. 

I chose to decline the first trimester screen and bloodwork.  However, at our next u/s they will do a quick look to make sure everything looks good and then if needed, I can do the bloodwork which I guess has to be done by 20 weeks.  

mcatmay

I've just done a LOT of research about this because i declined the first trimester screen and NT scan for the same reasons you did (it wouldn't change what i did in the long run and i would worry if i had a positive) and then ran into the issue of being asked for second trimester quad/penta screening. The old fears were raised again - looking into it, what you have to know is that there are both false positive AND false negatives. By combining the first trimester and second trimester screening both, then doctors have been able to predict more accurately the risk of down syndrome, trisomy18, etc... For spina bifida, i do believe it's from the second trimester screening, not first trimester.

I talked to the midwife, who wasn't hugely helpful but did say that, yes, there were a lot of false positives associated with second trimester screening. You can use the second trimester test more as 'screening' test to help you decide whether to do an amniocentesis or not - if it were positive for genetic abnormalities, then that might push you more into doing the amniocentesis than if it were negative.

However, your question was regarding spina bifida specifically and i'm not sure that you could tell on an amniocentesis whether your LO has that or not. You'll need to ask your OB that question.

Long story short, we decided NOT to do the second trimester screening for the same reason we declined the first trimester screening. At this point, i wouldn't trust the results one way or another, so why do it in the first place? I've known people that have had negative results and had a child with DS AND a heart defect that wasn't picked up prenatally and i've also known people that have had positive results and a healthy baby when it was born. If i decided to do it all over again, perhaps i would do BOTH first and second trimester screening but i wouldn't do one without the other.

 Sorry this was so long, just wanted to share what i'd learned about it. Good luck with your decision, it's a hard one to make.

cookie2279

Thanks everyone! Helpful info.

 Mcatmay--it's good to know i'm not the only one.  Thanks too for the insight into why the combo of the two screens is important.  I'll have to ask my OB more about the neural tube defects test and if it can be done in isolation.  Thanks!