More NT/CVS/amnio questions

[Anonymous]

I'm not the PP who posted about NT scans, but I wanted to follow-up to that post w/ a couple of questions. My doc tells me you get the NT scan after 11 weeks. Depending on those results, you can get the CVS, but it has to be before 13 weeks. My understanding is that the NT scan will give you odds, but the CVS is diagnostic (i.e., yes or no). If that's correct, then what is the purpose of the amnio? Is it just for people who missed the window for CVS? Or is the CVS not always accurate? Or does the amnio tell you other things that the CVS does not?

TIA!

[Anonymous]

I just went through this. It was my understanding that amnio and CVS are the same thing...CVS you can just do earlier, which has its advantages. And you are correct about the NT just being odds versus diagnostic. We thought we were going to do a CVS but when the NT results came back with the best possible odds we decided that was enough for us. Good luck! I found it nervewracking to make these decisions - and even switched practices over it.

[Anonymous]

I thought that the CVS was supposed to be riskier than the amnio? Not sure. The NT gives you odds, but then you compare the odds. For example, a good NT result would be your chances of having a baby with down syndrome is 1:5000; then you compare that with the amnio, which has a miscarriage rate of 1:400. Then you decide if it's worth it.

[Anonymous]

I had the CVS at 11 weeks and it honestly isn't riskier than the amnio (we spent a lot of time with a genetic counselor). The reason that there is a connection with an increased miscarriage rate is the time that the CVS is done (11 weeks) vs. amnio (20 weeks) as the risk of miscarriage with anyone is higher in the first 12 weeks.

My OB counseled me this was: If the outcome of the CVS or amnio with change your decision about how you carry out or not carry out your pregnancy, than the CVS is your best bet as you can have the test and get the results before anyone will know your pregnant

[Anonymous]

Amnio and CVS test for the same things, except that the amnio also tests for neural tube defects like spina bifida. That said, you can have the CVS at 11 or 12 weeks and then do the AFP blood test at 15 or 16 weeks to learn whether there might be neural tube defects.

[Anonymous]

I think CVS is more limited in the kind of diagnosis it can make and amnio is more through - I know I want the amnio as I am not really concerned with down but with a bunch of stuff.

[Anonymous]

CVS used to be riskier than amnio, but I believe right now the risk of miscarriage is about the same for both procedures. As PPs mentioned, one advantage is that the CVS can be done much earlier - I think you have to wait until 16 or so weeks to be able to do amnio.

[Anonymous]

CVS tests for 2500 genetic conditions so it is pretty thorough, plus you can get preliminary results in 48 hours. We got pretty bad NT results and had a CVS done right away and it was a breeze. We did it Wed afternoon and by 2:00 pm Friday had confirmation that our baby had 46 chromosomes with no abnormalities. Won't lie, those 48 hours were HORRIBLE, but having definite confirmation that everything is OK has been priceless.
Depending on where you have it done and the expertise of the doctor both CVS and Amnio have more or less the same risk, but as a PP said all women have a higher risk of miscarriage during the first trimester so the actual risk of the CVS is hard to gauge.
Good luck with your decision!

[Anonymous]

The CVS and amnio do test for the same things. At the later date they have more information for diagnosing the neural tube defects. Unfortunately or fortunately, however you want to look at it, they could see my baby had anencephaly at 11 weeks during the NT exam.

[Anonymous]

Anonymous wrote:I'm not the PP who posted about NT scans, but I wanted to follow-up to that post w/ a couple of questions. My doc tells me you get the NT scan after 11 weeks. Depending on those results, you can get the CVS, but it has to be before 13 weeks. My understanding is that the NT scan will give you odds, but the CVS is diagnostic (i.e., yes or no). If that's correct, then what is the purpose of the amnio? Is it just for people who missed the window for CVS? Or is the CVS not always accurate? Or does the amnio tell you other things that the CVS does not?

TIA!

CVS and amnio are the same thing in that they both look at the baby's chromosomes. The way they collect material to do that is different, however (google to get details), and CVS is considered somewhat riskier. The advantage, of course, is that it can be done weeks earlier.

When I had the NT scan, I was told NT scan has to be done between 11 and 13 weeks, and CVS can't be done after 12 weeks. So even if you want a CVS based on concerning NT scan results, it's very, very difficult to make that time window. I asked the nurse what people do in this situation and she said they wait and do amnio.

Based on that, my understanding is that people who do CVS know from the start they're going to do it anyway--they're not usually doing it following an NT scan.

Hope this helps! I realize others may have heard differently.

[Anonymous]

Something to bear in mind, too, is that if you have multiples the NT is not as accurate, because it relies on blood tests and ranges, and with more than one baby they told us there was a much lower rate of accuracy.

[Anonymous]

to the 12:46 poster -- the latest you can have the CVS done (according to the Genetics and IVF Institute in Fairfax is 13.5 weeks). I went in early for the blood test (at 10 w 6 d) so that I would have the results of the NT after the sono the following week and could make the decision the same day for the CVS. It can be done without waiting for an amnio.

[Anonymous]

Anonymous wrote:CVS tests for 2500 genetic conditions so it is pretty thorough, plus you can get preliminary results in 48 hours. We got pretty bad NT results and had a CVS done right away and it was a breeze. We did it Wed afternoon and by 2:00 pm Friday had confirmation that our baby had 46 chromosomes with no abnormalities. Won't lie, those 48 hours were HORRIBLE, but having definite confirmation that everything is OK has been priceless.
Depending on where you have it done and the expertise of the doctor both CVS and Amnio have more or less the same risk, but as a PP said all women have a higher risk of miscarriage during the first trimester so the actual risk of the CVS is hard to gauge.
Good luck with your decision!

We were in the same situation, sort of. It was a given that I was having a CVS, given my age and m/cs, but unbeknownst to me, the dr. did a NT fold before the CVS. We also got a bad NT results and had the worst 48 hours-my heart literally raced for 48 hours-but then when I called the office at 3pm, we knew our baby was healthy and a boy.

We decided to drive to Phili from DC and have the CVS at Thomas Jefferson. Supposedly, they were pioneers in the procedure, and came with high recommendations. The key is to find a dr. who has performed over 500 procedures. I was able to enjoy my pregnancy without the stress of the unknown.

[Anonymous]

When the CVS can be done seems to depend on the doctor. I just spoke to someone at Wilson Genetics who told me they'd do CVS until 12w or 12w2d, depending on the doctor. Which, is pretty annoying, because I'm doing my NT scan at 11w4d (the earliest possible in their schedule) and they told me it takes around 7 days to get those results. So if there's an abnormality, I have to wait a month for the amnio? I asked about doing the bloodwork in advance and was told it wouldn't speed up the results.

I'm so annoyed -- the whole reason for doing the NT was to hopefully have some peace, and, if the results were abnormal, to get the CVS so that we could know and decide ASAP. Now, if the results are abnormal, I'm supposed to just wait a month for an amnio?