TTS, mono di, di di, placenta questions!

Ok I know mono mono is 1 sac, 1 placenta and mono di is 2 sacs 1 placenta and di di is 2 sacs, 2 placentas. Right? If I'm right you can get TTS with mono mono and mono di right? I know my girls are in 2 separate sacs. But I don't know if they have 1 or 2 placentas. Should the fetal medicine dr be able to tell that during an ultra sound? I just am wondering because I thought if they had 2 sacs and 2 cords they didn't have a chance to get TTS but from what i have read on here thats not the case? I though the Dr couldn't tell if that had 1 placenta or 2 until delivery. Am I wrong? Also again I know the girls are in 2 sacs. If they share a placenta does that mean they r identical or do they have 2 be in 1 sac with 1 placenta to guarantee they r identical? And if they have 2 sacs and 2 placentas does that mean less chance to be identical or ???? This is all confusing. lol
Tiffany

 

It really can be confusing, I know! Hang around here enough and you'll be a few years of college short of an MD on the topic.

I'll be back after I bathe my stinky kids and get them down for the night. If nobody has given you all the info you need by them, I'll type out some stuff for you. So maybe an hour or so?

 

Okay, I'm back. You're right about the definitions of mono and di:

mo/mo (mono/mono)- One placenta, one amniotic sac. Absolutely identical.
mono/di- One placenta, two amniotic sacs. If truly mono/di, absolutely identical.
di/di- Two placentas, two amniotic sacs. Fraternal (with rare exception, I'll not get into because other people here are more educated on it than I and it's extremely rare).

Here's the two places where it can be confusing until after delivery-

Mono/di twins have one placenta. Sometimes, though, in the case of di/di twins, the placenta will fuse and appear to be one on ultrasounds. It's virtually impossible to tell. I think that in all cases where there appears to only be one placenta, they are assumed to be mono/di (and thus, higher risk) until delivery.

Di/di twins can absolutely be ID. I think it's something like 25-30% end up being identical. It has to do with how early the egg splits.

Mono/di twins (and mo/mo twins, anybody? I think only mono/di) are the only ones at risk of developing TTTS. Twin to Twin Transfusion Syndrome has to do with both babies sharing the nutrients of one placenta. The risk is that the one baby will become the "recipient" and gain more nutrients from the placenta than the "donor" baby. The reason you see the different levels of amniotic fluid when TTTS presents is because amniotic fluid is recycled from each baby. The baby with the greater input of nutrients will have the greater output of amniotic fluid. For more (much better) info on TTTS, visit the TTTS Foundation.

I hope this halpes clarify some of it for you! I know it can be an overwhelming amount of information at once! Good luck and keep updating us on your progress!

 

Stephanie you rock! Couldn't have answered this any better myself!!!

 

Just want to add, I'm pretty sure with di/di twins, the placentas almost always fuse at the end. And if you get an ultrasound really early on, they can usually easily see if they are di/di.

 

Mine were di di and still had separate placentas when they were born.

 

If depends on where the placenta's are. With miy girls one placenter was in the front, the other in the back ( anterior and posteria). There was no chance of them fusing.

 

I know that when you have an u/s early on the doctor can tell a lot better, but as the babies grow the placenta can fuse together and look like they share. so most likely they would have to exam the placenta after birth to be 100% sure. I had an u/s at 5w 2d and the sacs were apart so we could tell.

 

Both mono(chorionic)/mono(amniotic) and mono(chorionic)/di(amniotic) are at risk for TTTS; in other words, whenever a twin pregnancy is "monochorionic" it's at risk for TTTS.
TTTS can occur when there is one shared placenta which is the case with both mono/mono and mono/di. I was mono/di and developed TTTS.
Monochorionic always means identical.
Dichorionic can mean identical or fraternal.

 

See, I thought so! Then I started thinking about the amniotic fluid issues associated with TTTS and felt like I was getting it wrong. Thanks for the clarification!

 

My twins were di di, with an anterior and posterior placenta and completely separate a birth. My boys are very obviously identical, but we did have it confirmed with genetic. Testing.