Screening after previous trisomy 21 pregnancy

[blacktreaclecat]

I'm in a dilemma. We tfmr earlier in the year after a 11mm nuchal - t21.
We are now pregnant again - 8 weeks after array cgh ivf.
Array cgh is a technique where one cell is taken from a day 3 embryo and the chromosomes checked. The blastocyst we had transferred came back normal.
Array cgh like any other test has a chance of being wrong due to mosaicism. The chance of being told a normal embryo is abnormal is much higher than the chance of being told an abnormal one is normal.
We are under fetal medicine as we have had a previous abnormal pg. At the moment we have had one scan where we saw the heartbeat and we have another next week. Our consultant knows it is an ivf pg but we haven't discussed the array cgh thing yet.
We will be having the nuchal scan at 11 weeks and are obviously hoping for a low risk result.
Just can't decide what to do about cvs. We are likely to be offered it after last time but I don't want to risk mc. What to do? I don't know if the array cgh can be taken into account when calculating the risks. Also if the nuchal is raised there may well be a problem, just not a chromosomal problem.
I'm all mixed up- any thoughts?

[bezzyk]

Congratulations!

We were in a similar situation (ok, not with the ivf, but with previous T21 pregnancy, as well as a T13)

In the end, we set a figure in our head, as odds that we'd be happy with, in order to avoid CVS. I think it was 1 in 500. As it turned out, odds for DS were 1 in 7845, so was a bit of a no-brainer, so decided against the CVS, and the other trisomies were even better odds.

Hoping the next 3 (ish) weeks pass quickly for you xx

[ghislaine]

I think it's something only you know how to weigh up. When I had this scan this pregnancy, the consultant offered me cvs before the scan and asked what numbers would make me not opt for cvs. The real answer was that no numbers would do that. I did have the scan anyway because I wanted to know as much as possible before I had cvs but I was prepared to take the risk of miscarriage to get certainty.

[mrsbigz]

hey hun, so happy that you've had one scan out the way and seen a heartbeat :)

i echo what the other ladies have said - it is a very personal decision. as you know we also ended our pg earlier this year due to t21 and CH.

i wanted to do everything possible to avoid invasive testing if i could, so we opted for a private nuchal (our nhs nuchal didn't do the nasal bone / other soft markers as standard - even with our history). the private nuchal scan came back all good, nasal bone present, and our odds for t21 were 1:1700 which were good enough for us (considering last time we had 1:5 odds) so didn't have the cvs or the amnio. we are being scanned every 4 weeks- and as you know our baby's been diagnosed with CCAM, but this is something completely unrelated to chromosomal problems and we're being well looked after.

i think once you've had your nuchal scan you will know what to do - but considering the array ivf i think you will be absolutely fine - and i would tell them this when you have the nuchal so that they can take it into consideration

sending lots of love xxxxxxxxxx

[glimmer]

Hi blacktreaclecat. The consultant will know only little about array cgh ivf riscs.
It seems that the risc of mosaicism is extremely low, but only a geneticist will be able to give you a better idea. Localized mosaicism is more likely in the placenta than the embryo, so they will be prefer to give you an amnio rather than a cvs.
Thing is - even if you have cvs or amnio - they only look at what - 10 or 20 cells, so you can never avoid the risk of mosaicism completely.
I understand that you want certainty and what being the 1: xxxx means. All the best.