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Diamniotic Monochorioinc Twin Pregnancy?

Hi all
We just had the 12 week scan today.
We were told that there was a T sign present. There appears to be a single placenta suggesting a diamniotic monochorionic twin pregnancy.
We asked if that meant they were identical, but she just said, not really.
Can anyone tell me what it does mean.


  • Hi,

    I understand that diamnitoc monochorionic twins are usually identical, they share placenta's but not sacks. If babies share placenta as seem to be in your case then they are nien times out of ten identical. However, even at 12 week scan it can be too soon to see if there is one placenta or two joined together, so they may do another scan to check later. I havent got a clue what the T sign means i ould suggest having a look on the TAMBA site, they are quite handy to join, as they have lots of info on twins and more and also you receive vouchers and things towards the cost of puschairs etc..

    Sorry i cant be more helpful but hope that helps a bit.


  • Like Sarah said it is difficult to tell for certain at 12 weeks as placenta cld have fused but diamniotic, monochorionic twins are by definition identical. (non id are dichorionic)

    The fact they are diamniotic is a v good sign as id twins develop much better if they have their own sac.

    You shd be offered another scan at 16 weeks to check they are monochorionic then she shd be scanned every 2 weeks from 20weeks at the latest as with id pg their is a risk of twin to twin transfusion whic if caught early enough can be corrected. (TTS is where 1 takes more nutrients so grows quick, whilst other isdeprived. I developed this towards end of my pg, but all ok in end)

  • I'm having MC/DA twins. We found out at an 8 week early scan and have been told they are identical and therefore same sex. The babies are in one sack (chorion) with a separating membrane between them, share a placenta and have separate amniotic fluid (this is the diamniotic bit). In terms of scans. I started having fortnightly scans at 16 weeks to check fluid levels are equal and growth is even (TTTS). Good luck with your pregnancy xxx

  • Hi - yes, monochorionic (one placenta) means identical twins. Basically they have come from the same egg. Non-identical twins come from different eggs so have different placentas (dichorionic).

    I actually had a monoamiontic monochorionic pregnancy (one amniotic sac only). It was pretty high risk & I was scanned twice a week in the later stages. It's much better if there is a dividing membrane (dioamniotic), so it's good that you have that type. That said everything worked out fine for me, although I did have to have them early.

  • Hi, I am 20+4 carrying monochorionic diamniotic twins and we were told at the 12week scan that there was a seperating membrane between the two which we could faintly see on the piccie and they were sharing the same placenta. On our 20 week scan ( last Friday ) we were told they are girls ( YIPPEE!!! - we already have a superstar boy 6yrs ) but the sonographer thought that perhaps the placenta was two not one as she couldnt see it too well. So that then calls into the question the ID bit but we are now having scans every two weeks so will hopefully get this clarified as we go on. So still not buying pink or blue until we are positive as sonographer seemed less than positive ( perhaps they have to be?? )
    Anyway - good luck and if your babies move about as much as mine you will have great fun!!
  • We have had to go through I.V.F. so we thought that the 2 eggs they implanted had both fertilised.
    Now it may have been just one egg. Still not sure as our twins specialist is on holiday and were not seeing him until 2 weeks time. The next scan is'nt until late march. Should we push for an earlier one.
    Have'nt been told anything for certain.
    14 weeks
  • I think you should be entitled to an earlier scan than late March if it is confirmed what type of twins you are having. I'm sure, when you see your consultant in a couple of weeks, he will pick up that there is a possibility that you could be carrying Mono/Di twins and will put you on the relevant scan cycle. If not, please do ask to put your mind at rest! Good luck and keep us posted xxx
  • Hi! I am 28+3 with MC/DA twin boys who are identical. Everything is going well so far and twins are both good sizes. Having scans every 2 weeks which is very reassuring. How long is a MC/DA pregnancy usually, does anyone know? Jane x
  • Hi Cuttsy def ask for an earlier scan, prob with IVF is that they just assume its non id thus dont need to scan as often but if it is id (and this is not related to the fact you had IVF) then you need scanning every 2 weeks from 16 weeks to pick up if TTS occurs.

    Four angels MC/DA usually are delivered by 37.5 weeks, but much higher chance of them being delivered early if they are ID

  • Should definitely be on more frequent scans i was on 3 weekly scans to start with and then weekly and i was having fraternal twins!!! Although eventually had my girls at 33 weeks!
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