Twins and Multiples Forum

Posted: 09 September 2007 at 11:18pm | IP Logged

Does anyone out there know anything about twin to twin transfusion?

My twins were born 6 weeks early because of it, and were quite poorly, thankfully they are both ok and havent suffered any after effects, and are both gorgeous and doing well in school.

When I asked what caused it after they were born , all the proffesionals I spoke to passed it to someone else and I never really got a satisfactory answer.

Can anyone shine a light on this?

Posted: 10 September 2007 at 7:10pm | IP Logged

Hi welcome to Madmums. 

Twin to twin transfusion only happens with identicals whether twins or more. 

When the egg is first fertilised it implants in the womb and the 1 egg and 1 sperm split to make identical twins or more.  When the egg splits to make more than one baby determines what sort of identical twin they are and whether they are at higher risk of ttf. 

If the egg splits in the first 4 days they will normally share the outer layer of the amniotic sac but have individual inner layers so be in little sacs of their own, they often will have 2 seperate placentas, these babies are not at risk. 

If the egg divides from 4 to 8 days after being fertilised they will often share the outer amniotic sac, have seperate inner sacs but only one placenta. 

If the fertilised egg splits at 8 to 14 days after fertilisation the babies will be in the same inner and outer sac and only have one placenta.

The babies that only have the one placenta are the ones that can suffer ttf. 

With monochorionic twins (twins that share the same placenta) blood vessels within the placenta can form a link, they can form different types of links artery to artery, vein to vein or vein to artery.  So within the placenta an extra blood vessel can grow that takes the blood from one twin to the other, this is twin to twin transfusion. 

You end up with a twin donor and a twin recipient.  The babies are totally normal it's the placenta that has the problem. 

What happens is the blood from the donor twin is transfused (given through the abnormal connection) to the recipient twin. TTF can happen at any time in the pregnancy but normally in the 2nd or 3rd trimesters.  TTF may not happen until birth as well so that babies that don't show any signs of TTF can have problems at the time of birth. 

The recipient twin will be larger than the donor twin due to the extra blood.  The extra blood can overload the recipients little body and their heart has to work a lot harder to pump all the blood around. 

The donor twin on the other hand can become anemic and underweight due to not enough blood they will also have very little amniotic fluid surrounding them if they are in a seperate inner sac.  When the donor baby survives the birth it is often the stronger of the 2 babies even though it is the smaller as there has been no strain on its heart. 

There are things that can be done if the problem is detected on Ultra Sound Scan early enough (that is why regular ultra sounds should be carried out from the 2nd trimester onwards at least every 2 wks increasing to every week), even interuterine surgery can be carried out where they use a laser to seal off the abnormal blood vessels within the placenta.

Posted: 10 September 2007 at 8:31pm | IP Logged

Thank you for that folks, will check out the website.

Do you know what causes the abnormality in the first place Sam? I spent a very long time worrying that it was something I had done wrong during my pregnancy, or something I should've done but didn't.

It doesn't really make much difference to the boys now as they are very lively healthy 7 year olds, but it would certainly give me some peace of mind.

Posted: 10 September 2007 at 8:44pm | IP Logged

Hello and welcome.

I have identical twin girls of 2 and i also worried about this. They shared everything includeing the sac so was kept a close eye on.

Luckily my girls were fine apart from being 8 weeks early. To be honest you didn't do anything. Twin to twin is just something if its going to happen then it will. There is absolutely no fault of your own that this happened.

I cannot add to what Sam has said but you didn't do a thing. xxx

Posted: 10 September 2007 at 9:46pm | IP Logged

There is nothing you did or didn't do that could make the abnormal blood vessels grow they just do. 

They think that it happens with all twins that share a placenta but that the ones it doesn't affect is because the blood vessels balance themselves out so one will go from one twin and one from the other so it doesn't affect them in the same way. 

The placenta is an amazing organ and extremly large organ too, it has a very short life span only 9 months and develops rapidly in that time.  If you consider other organs that grow which can also have little defects that sometimes will cause symtoms and sometimes won't it's easy to see how it happens.  For example the heart some valve defects in the heart in one person it will be life threatening to somebody else who may have the same defect but never notice it.

With such rapid growth of the placenta it's easy for it to lay down too many blood vessels.  If the placenta was sustaining only one baby it wouldn't matter it's only because two babies are being sustained from the one placenta that it's a problem.

There really was nothing you could do now or then.