I'm asking this question on behalf of my cousin and his fiancee. They had a previous pregnancy in which the baby had Downs, and just found out they are pregnant with twins. Her doctor suggested that, in addition to the MaterniT21, they do CVS on the twins. My question is...if (fingers crossed) the MaterniT21 comes back 100% normal, why would they do an invasive procedure like CVS? Is it normal to do both tests on someone who has a history like theirs as a matter of course? Thanks for weighing in!
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Technically the MaterniT21 test is not a diagnostic test, it only tells you the potential risk as a percentage, while CVS is a diagnostic test. If the MaterniT21 test is "positive" (indicating high risk) then CVS or ammnio should be ordered to diagnose if the condition is present, yes or no. If it were me, I would choose to do the MaterniT21 and then do the CVS/ammnio if the results come back high or just go straight ahead with the CVS and not do Maternit21 testing at all. The MaterniT21 test should be accurate with twin pregnancies (according to their own literature, I would double check to be sure), so I don't know why the doctor would want to do CVS in addition. Hope that helps
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@Ms.Badger: I agree with you. I'm curious if materniti21 would be accurate for gender based disorders though. That wouldn't affect down's but we recently had a bee with turner's syndrome and that is a disorder related to baby's gender. So I think you're right about having her look into those details with the company.
Personally if down's is the only concern I'd do the blood test over the CVS or amnio, which have miscarriage risks, at least until you were given a high result and needed to be more invasive.
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A cvs tests for over 200 generic disorders some of which are awful. The blood tests only test for a few. I've read that there is a 1 in 100 chance of getting one of those disorders that the blood tests don't catch.
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What @Ms.Badger said is exactly what the genetics counselor told me a couple of weeks ago (except I had the Panorama screening, and they said it does not work with twins, not sure what the difference is). I think with their experience, I would consider going straight for the cvs. The miscarriage risk is pretty questionable, since it's done early enough that there's no way to know if you would have miscarried anyway (and they're testing for conditions that can cause miscarriage, so women having the test tend to already be higher risk). The only reason we did the screening first was because A) R's issues were not genetic, so technically we had no history (unlike your cousin), and B) we had already done full genetic karyotyping on ourselves, so we knew our risk was very low.
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@Ms.Badger: Thanks-yes, you're right, M21 isn't diagnostic. I just wondered why her doctor would order it simultaneously, rather than waiting for the results to do an invasive procedure like a CVS?@marionberry: Exactly, if it were me I'd personally wait on results of blood tests before doing CVS or amnio. It being twins threw them for a loop. so now they're trying to find the best possible doctor for their unique situation.@raintreebee: Thanks for your input...I'll let them know about how much more expansive CVS is as a diagnostic test.
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@ChiCalGoBee: I'm having twins so I get how that affects testing options. Have them connect with a really good maternal fetal medicine doctor. Most MFM offices have really experienced genetic counselor who can guide them in the right direction.
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@Torchwood: I so appreciate your perspective, especially with all you've been through. I'll pass along your thoughts to them. I hope you're feeling awesome and that this is a healthy little baby for you!
@marionberry: Thanks for recommending they see an MFM! Great advice. Congrats on your twins:-). -
A CVS looks for tons of stuff. Maybe downs also put her at risk for a plethora of other genetic diaorders, so she's casting the net wide. I had one done instead of just a blood test because it was far more comprehensive. My NT scan and blood draw gave me higher risk markers for a few things, but nothing definitive. My dr was concerned E could have turners syndrome....I can't remember all the reasonings, but I ended up going straight to the CVS. I was referred to an MFM physician, who did the procedure. My OB doesn't do them. They make you see a genetic counselor first. They took blood from me for it. I also had a FISH array done....so that could be the "cvs and blood test" part
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