Identical Twin Preg. +ve result for downs :(

[LindyLou71]

Hi - New to this forum.  I am 39 years old with a very healthy 22 mth old son.  Found out we are pregnant with identical twins.  Decided to do the prenatal screening at 12 weeks.  Ultrasound was good. NT Twin A =1.4, B= 1.8.  Decided to do the bloodwork - they called today - a positive result for DS.  Twin A - 1:310 (which isn't bad) 1:70 which concerns me.  I guess I have a lot of questions for the Genetic Counselor on Monday.  But since they are identical (one egg one sperm) wouldn't they both have it or not have it?  Also how do they separate my blood to give 2 readings?  I am thinking about lots of things including Amnio.  I didn't know about doing the more involved US first? to measure the femur, the presence of a nasal bone etc.. wouldn't they be able to see all this?? My Doctor initially didn't recommend the blood work b/c of the false positives and with 2 it gets even more complicate.  My gf who had Fraternal twins only had the option of Ultrasound.  Just looking for a little advice and support.  Thanks :)

[55555mlk]

(NEW TO FORUM AS WELL) I have worked in a ob/gyn office and I have had twins as well fraternal, the test that they have pt's take for the ds screening has a high rate of false positive results and as a result I refused those tests for myself I have seen too many parents go thru the agony of those results being positive when there was actually nothing wrong with the baby or babies.....have an amnio and hat will give accurate results....the amnio fluid will tell you everything I had several of them as well as bpp (bio physical profile) and ultrasounds 3 times a week, I I had pre-term labor and I have Lupus....... 5 children later they are all healthy and my last one was at the age of 36.  try not to worry until to see the specialist and have an amnio, ultrasounds can identify ds as well in the features/measuring. I think they should discontinue having pt's take the trest because of the HIGH RATE OF FALSE POSTIVE RESULTS .  try not to worry and have the amnio.....GOOD LUCK AND CONGRATS              

[stay717]

We just found out on Friday that we are pregnant with twins.  Shock still has not set in....but I have already gone down the road of "what if's".  I did ask my doc on Friday about this. I didnt understand how taking my blood they could find out if something was the matter with 1 or both twins, and also how to find out which twin had something wrong (IF there was something wrong) He told me that I would come back in in 4 weeks for another ultrasound.  (when I am 12 weeks- 8 weeks now).  So, next month he said they will take more blood from me and measure the necks of each little guy in there.  From there they could tell how they were growing and IF there may be an issue.  he also mentioned a process called CVS, (i think that is what he said....this was all so fast and after a VERY big shock). but this was different than amnio.  An Amnio takes some of the fluid from each sac, but the CVS test will take a piece of each placenta, which they can get much more information from. They either go through the belly (like amnio) or up the cervix. (EEEKK!!!)

I wish you all the luck in the world.  I am more than confident that I will be back on this board posting all of my questions and concerns.  For the time being, I am patiently waiting to see if both make it to 12 weeks.  (good HBs, but one was measuring bigger than the other)  Oh- mine have separate sacs and separate placentas.

Good Luck to you and both your little ones!!! Prayers and hugs your way!!

[LindyLou71]

Hey - I didn't think you were judging at all - it was refreshing not to see "if you aren't planning on terminating then don't do it"  I need info like you.  I am glad your LO is doing so well.  I am nervous with 2 coming!

I am feeling a bit more rationale today and will try to formulate appropriate (non-emotional) questions for Monday.  I live in Ontario and in my area there are 2 hospitals that have it available and are extremely reputable we may interview both.  I am only 13 w 3 d so I have a bit of time,  the info online recommends after 16 weeks.

Thanks again

[adgal]

Please don't think I am judging one way or the other.  I just often see responses to posts about amnio that say things like "if you wouldn't terminate anyway, why bother" as there is a bit of risk involved with amnio.  I am like you, knowledge is power, and wanted to know exactly what was going on.

If memory serves me correctly I was about 16 weeks when I did the amnio.  The risk associated that is the generally accepted number is about 1:400 (where the amnio causes miscarriage).  I pretty much interviewed the perinatologist who was to perform the procedure, and asked a lot of questions at the clinic in general.  There ratio was more like 1:1600 as he was very very experienced.    They did not offer any other tests prior as I wanted 100% definitive answers and this was the only way.  The procedure itself was really easy...and I am one of those who is absolutely terrified of needles.  It looks intimidating, but I have experienced more discomfort having freezing at the dentist.  It was ultrasound guided and they waited until my son was in the correct position, then it was over very quickly.  A bit of a sting (much like a bee sting), mild pressure (very mild) and all done.  I had the procedure on a thursday, took the friday off of work as well and just took it easy the whole weekend.  No lifting or anything.  I actually took the 24 hours take it easy instructions to the extreme, but figured it couldn't hurt (besides, it was nice having my husband wait on me..lol).  I was back at work on the monday and all was absolutely fine.

I opted for something called FISH.  Typically results take about 2 weeks (at least here they do).  FISH gave me my results in 3 days.  It is a slightly different, accelerated way of looking at the cells and is app. 93% accurate instead of 99%. But I am impatient and the unknown is pretty much the worse thing for me, so I took that option.  I got my results on the monday, all was fine.  They still tested the cells the normal way, so I got another call in about 2 weeks confirming everything was fine.  He is now a healthy, happy and very active 8 month old.

For me it was absolutely the right decision and one I would make again. As I said, the unknown is the worse thing for me and knowing what was going on made my pregnancy that more enjoyable.  

Any other questions, please just ask!!  

[LindyLou71]

Thanks for your post.  1:13 is a high ratio too.  We almost didn't do the Bloodwork b/c the u/s was good.  But we did and now we have the results.  I think the choice to terminate is an individual one and we are not there yet by any stretch.  It's more of a fact finding mission especially with TWINS.  One child with DS would be challenging (and rewarding) but two maybe more than I / we could handle and I have a 2 year old who still relies on us.  I would want the amnio more as a definitive answer than to be the rationale for termination.  Can I ask how many weeks you were when you did the amnio?  Did they offer you another test prior?  I imagine my age 39  - is causing a lot of this but I guess you just don't expect that call :).  I would appreciate any info on amnio you would like to share - anything you did leading up to it - days of rest?, how quick were your results? etc... Really appreciate it - I am a knowledge/researched based decision maker :)

[adgal]

Congrats on your twins!!  I didn't read all of the other posts, so I apologize if I repeat some of what may already have been said.  First off, first trimester screen is not a diagnostic test, so don't let the results scare you.  All it does is measure odds, which if you put into perspective are very much in favor of them not having DS.  My first trimester screen for my son came back 1:13.  He had no physical markers, so the results were also based on bloodwork combined with my age (I was 40)  I opted for amnio, and he does not have DS.  I can also tell you that I have a few on line friends here who do have babies with DS and I am no longer afraid of it.  They are gorgeous, perfect babies.  

I really wish they would not use words like positive with first trimester screen.  It just scares us for no reason.  If you have any questions on amnio, feel free to ask.  For me it was a relatively easy procedure with no side effects and gave me my answers quickly.  Some feel that amnio is only for those who may want to terminate...not true.  I wouldn't have, but I did want to know one way or the other so I could be prepared.

Good luck with whatever you decide!!!

[LindyLou71]

Thanks for the comments.  The are considered Mono/Dia twins basically one egg got fertilized by one sperm and the DNA split.  So inside one sac is 2 embryos.  They have the fortunate situation of having a small membrane between them and each have their own placenta but they are definitely TRUE identical twins.  They will be the same sex, look alike their only differences will be fingerprints.   SO that being said I also felt that if one was affected then the other would be too.  

I think peace of mind more than anything else with the Amnio.  I may opt to do a more invasive ultrasound and the blood work first.  As I read more about the soft markers I see that there are  some other things they can check for.  - Nasal bone, heart, femur etc.... I have so many questions.  Sigh.....keep the comments coming!

[happynifer]

the different ratios come from the nuchal ligament measurements being different, not differences in your blood test.
you cannot have more than one sperm fertilize a single egg....
this is just statistics giving the risk of a baby or babies having a chromosomal abnormality.
what you need to decide is what you would do with the information if you went through an amnio vs the risk of miscarriage from the amnio.
but the amnio is the only way to know for certain.

[oceanv]

well, i had 1:400 and my baby did not have downs, unfortunately amnio is the way to go if you are worried

[worried2451]

WHAT!??? How did the lab get 2 results from the blood work alone? Or were the NT's factored in to give 2 readings?

[jakl726]

first, congratulations on your twins.
this is a very interesting (and intriguing) subject.  i'm sure you know identical twins results from a fertilized egg (1 sperm + 1egg) dividing into two zygotes (or embryos).  therefore, the same genetic make-up.
i am thinking two reasons why one MAY be positive for down and the other not.
(1) two sperms (instead of 1) fertilized the egg.  one sperm carried the abnormal chromosome and the other sperm was normal.  and so when it divided, one embryo got the faulty sperm and the other embryo got the normal sperm.
(2) maybe you are having fraternal and not identical... though if they found only one placenta (vs two for fraternal) then you are definitely having identical.  just a wild guess :))

as for the blood test... your blood is their blood.  if the result for down is only 50% vs 100% then they (the laboratory people) are assuming that only one of the babies have down.

again these are all wild guesses from the little biology that i know.  very very interesting... please let me know what your doctor says. :))
MOST OF ALL... good luck. :)