Identical Twins: Scans

[TigerCub07]

Hi,
Is this normal?

I'm 21 weeks pregnant with identical twins and I'm having a scan evey 4 weeks (12, 16, 20, 24 etc). Is this normal?

Also, people keep asking me how I know they are identical as when their sister/friend/cousin/stranger on the street etc had twins they were told there was no way of telling if they are ID or not in utero. Again, is this true??

Hi - I have ID twins and I was scanned every 4 weeks. I think this is normal with twins - if there were any potential problems with your pregnancy I think they would see you much more often.

The ID thing is tricky... We didn't find out that ours were ID until after they were born, as I had two sacs and placentas. The only way to know for sure was through a DNA test. They looked very similar on some days and different on others, and had different head shapes and moles. Confusing! But ID they were.

I assume you have two sacs but that your babies share a placenta. In that case I think they are likely to be ID but it could still be that two placentas have fused and that they could be non-ID. I think the only way to know for sure that they are ID is if they are MCMA twins who share both a placenta and a sac. That's a very high risk pregnancy and it doesn't sound like you're one of those.

So when people ask, maybe just say that 'we think they are ID'. It's confusing to a lot of people - many talk about having 'non-ID' twins when their babies have separate placentas, which is wrong too, unless of course they are different sexes.

This is a good website for clearing it up (look at the very bottom of the page) and finding out about DNA testing, if you should ever consider it. Good luck with your pregnancy!

Thats interesting 2to3, my non identical boys 3 months, are looking more identical each day and everyone presumes they are.
One is still bigger than the other though and one has more hair. Confusing

Hi - ID twins can be different sizes and have differing amounts of hair, different birth marks, head shapes, etc. They key is whether they have the same eye/hair colour and look a lot alike overall. It's wrong to say they're non-ID just because they had separate sacs and placentas - 1/3 of all ID twins do.

Highly recommend taking the DNA test to be sure - I hated not knowing and felt it was important for them to know too. It's completely painless and £80 well spent. See link in post above for how to do it.

At nearly 5, our boys still look a lot alike but it's amazing what different haircuts and clothes can do !

I have ID twins and had scans every 2 weeks as they were sharing a placenta and therefore there was a risk of TTTS. We were told at the 12 week scan that the twins were ID - the sonographer, and then consultant, explained that they could tell because of the shape of the placenta - the consultant pointed it out to me on the scan picture, but I was still in shock from finding out it was twins, so I wouldn't have a chance explaining it, I'm afraid. I had scans every 2 weeks until 32 weeks, then every week after that til I had them by elective c-section at 37.5 (twin 1 was breech, twin 2 transverse, so no chance of natural birth)

thanks 2to3 Think i'll save up for it, I'm 90% sure they are not identical but then sometimes like when they're asleep its difficult to tell them apart.
I've put a picture from yesterday on my profile what do you think?

Must of been worrying Kembletwins, my 2 had seperate sacs and placetas so thank goodness didn't have that worry.

Honestly? I'd say ID, definitely. Gorgeous children!

I'm no expert, but I believe that the majority of id twins share a placenta (in some cases the when the egg splits, each foetus has their own placenta and it is these cases where the testing process is useful). Some id twins also share an amniotic sac.

At the scans it is possible to see whether your twins are sharing a placenta or not, so easy to tell whether you are carrying id or non-id twins. So I'm pretty sure that in the majority of cases, your friends are wrong when they say there's no way of telling when the babies are still in utero.

But IME, you should be being scanned more often. My id twins shared a placenta and an amniotic sac and I was scanned every 3 weeks from 20 weeks onwards. Many mums of id twins I know were scanned every 2 weeks. The protocol for scanning twins is different at every hospital, but I am surprised that you are not being scanned more frequently. There are risks associated with id twins and more frequent scans are the best way of ensuring any problems are picked up so they can be dealt with in good time.

HTH

Ah thanks 2to3, think I will get the test done as am asked at least 3 times a day
are they identical?

thats interesting tkband3, I was only scanned at 12, 20, 28, 32 and 36 weeks does seem to vary from hospital to hospital.

There's no way of knowing if twins are ID or not until they are born - unless you know your babies are different sexes, or if they share both a sac and a placenta (MCMA).

MCMA twins are considered very high risk of complications so they are therefore scanned more often than babies who don't share a sac.

Babies who share a placenta can be ID or non-ID. The only way to know for sure is by doing a DNA test. See the link above at the very bottom of the page - it's explained in a very clear diagram there.

Gosh, 2to3, you seem very clear about this. I think having an unnecessary DNA test is really OTT. I was told by my consultant at my 12 week scan that my twins are ID, and she was able to explain how she knew that. To be honest, mine look bloody similar, so I'm happy to take the consultant's word for it.

Hi Kemble - I do have a bit of a bee in my bonnet about this, but I wasn't referring to your situation. If you are sure then there's no issue. The problem comes when your twins look very similar but you've been told they're non-ID.

I've met many parents whose twins look very similar, but who are confused because medical staff have told them they are non-ID without any scientific basis. I think it's a shame that people are prevented from knowing something so crucial about their children because of doctors'/midwives' ignorance. They should really offer testing for free in hospital when they are born if there's any doubt at all. If I was a twin I'd definitely want to know whether my sister shared my DNA or not.

As for my boys, it just felt weird not knowing for sure as everyone had a different opinion. Their grandmother was convinced they were non-ID, for example.

Fair enough. I agree with you that testing should be available free for those who want or feel the need for it. I suppose, given that mine are pretty obviously ID, I don't really understand. There's a mum at our twins group though who must get driven mad - she's been told her twins are non-ID, and the standard response is "really? But they look so similar". That must be infuriating!

The latest advice for mcda or mcma twins is to scan them every 2 weeks to keep an eye out for TTTS. I would contact the multiple births foundation for advice. I was scanned every 2 weeks.

I'm 22 weeks with MCDA twins and being scanned fortnightly. I also was told right from 10 weeks that they are definitely identical - one placenta, one chorion, two amniotic sacs. I think that means they are definitely identical? or is there a chance they could not be? they are both girls.

Weegle - look at this website - it's exlained there in a diagram at the very bottom of the page. The Multiple Birth Foundation basically says that MCDA twins are probably ID "if they share all the same blood groups". I don't know if that leaves you any the wiser, but it sounds like your situation is the same as Kemble's was (see posts above). If your consultant is sure and they look a lot alike when they're born they probably are ID.

Kemble - yes, that's exactly it. It must be super-annoying to be asked if you feel sure that there is no way they could be ID, because that's what you've been told by docs. But then how annoyed would she be if she found out that she's been given the wrong advice and that they could actually be ID after all?

it's not very clear on that diagram - but the third diagram from the left is MCDA (I think?) and that says 'identical'. ie. one placenta, one chorion (outer sac) and two amnions (inner sacs). Every consultant, registrar and sonographer who I have seen so far says definitely identical because of the mono-chorionic bit. It is quite confusing, but from everything I've read if they share that outer sac (which is more identifiable at earlier scans than later, I understand) then they are identical? However, you've clearly done a lot more research than me so I'll be willing to be corrected if I've misunderstood that! Will be a shock though since I've just got my head around the identical bit!

sorry, didn't scroll down far enough in that link - following that flow chart mine come out as definitely identical. Having the one chorion. The blood groups bit is for if they have separate chorions...

There you go. I've been looking into this from time to time for five years and still can't say I completely understand it!

I have twin girls who at the first scan were deemed to be MCMA and after kicking up a bit of a fuss at the hospital because my midwife assured a very tearful me that "there was nothing to be concerned about", the consultant I saw booked me in for fornightly scans from 12 weeks.

At around 22 weeks a membrane was discovered separating the two (the best sight of my life I think!) but they continued with the fortnightly scans, and just as well as dt1 stopped growing at around 31 weeks.

Anyway, i'd say unless there's a cause for concern, 4 weekly sounds about right to me, but do not be afraid to ask questions and ask to see other people if you don't feel quite right with what you're being told.

Also, I'm pretty sure (as sure as a mother can be) that dts are identical, despite being assured by old ladies on the street that they are definitely not as one is fatter, or that they can just tell them apart.

They are too similar to be just sisters imo. I'll post a pic on my profile and let the MN jury have a crack at deciding.

MCDA twins are likely to be identical. There is a small chance that they could be non ID but that their placenta's have implanted close and have fused together. This can be determined by having hte placenta studied after birth.

It also depends on exactly how the membranes are set up. MCDA twins may actually share the outer membrane, bith a single thickness dividing membrane. In this case they are def ID. If they have a double thickness membrane between them it is still up in the air.

Incidently as far as TTTS goes MCDA are actually at higher risk of developing it than MCMA.

At my hospital Monochorionic twins are scanned fortnightly. Dichorionic 4 weekly.

BTW I was told at 12 weeks despite them being MCDA that they were ID as the sonographer was able to measure the chickness of the dividing membrane. It was not definitive but she was obviously highly skilled!

Bibitthree I cant't see
the pic

I was told 1 placenta through out my 1st twin pregnancy. They weren't 100% but they thought i was having identical twins.

When my 2 boys were born i was told they were identical as it was one placenta, very thin membranes. They also thought they had TTTS as there was a 1lb weight difference.

I was not convinced, they looked totally different dark/blonde hair, different skin tones. I had the placenta tested and they were non-identical twins like i had thought all along!!

I got scanned every 4 weeks too, very reassuring seeing them on the monitor month after month.

I had one placenta, sac each - the less high risk of identical twin pregnancies. ID twins have to share a placenta, as far as I'm aware, because they come from same egg. The sacs depend on when the egg splits (with conjoined twins being where doesn't all separate early enough).
ID twins have same eyes, ears, hands, feet, but can have different hair, head shape and height. I am pretty certain they have same fingerprints - there's a pair of ID twin criminals in Bristol who are causing havoc as impossible to prove who is who at the scene of the crime(!). So there's our kids' future career he he he...
I was scanned every four weeks except when they though we were at higher risk of developing TTTS (don't even look it up on the internet as not worth the worry it will cause!), when we had a scan at 17 weeks and then at 19 to get the all clear. We then reverted to four weekly.
I think four weekly scans sounds fine, and wouldn't worry about asking for more as it allows you to focus on you and your babies, not the what ifs! Better to have less than stress yourself out - and you can always ask for one for whatever reason.

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