Fraternal now Identical?

I had my first ultrasound/ sequential screening at around 14 weeks where the sonographer and doctor were both adament about my twins being fraternal. I later switched hosptials and at my 19 week u/s, the doc suggested that they are identical because it appears they share a placenta yet have different sacs with a thin membrane seperating the two (if my memory serves me correct). I'm wondering how id were not spotted at the first u/s and/or could it be that the two placentas simply fused to look like one??? I now have to have ultrasounds every two weeks; are frequent visits necessary for fused placentas as well?

 

the additional ultrasounds are necessary only because they can't know 100% whether it's one placenta or two fused together - they won't know until after babies are born. unless they were clearly two placentas on the first ultrasound. although, even if they are two separate placentas, your babies could still be ID. so while the doctors at the 14 week ultrasound may have been sure they saw two placentas, it was premature of them to say that your twins are ID, if that makes sense. i would ask your doc at your next appointment why the change & ask about the possibility of fused placentas.

 

I was told I definitely had 2 sacs and 2 placentas at my first ultrasound like you. I even thought it looked like one big sac. So I did some research and convinced myself. LOL They were wrong. Turns out it was only one and my guys are definitely ID. The extra monitoring shouldn't hurt, even if they don't know for sure whether it's 1 or 2 placentas. Congratulations!

 

I was told fraternal all along so far because of how thick the membrane separating my twins is, plus I have the twin's peak sign which indicates fraternal. This last time the ultrasound tech told me I could still be having identicals, so I'm just going to hope they are still fraternal and bring some nail polish to help tell them apart just in case.

 

Wow, that must seem really confusing to you. :hug: I agree there is really no way now to know until after they are born and test them. At this point you never know whether they share a placenta or the two fused together. Rachel gave some great advice and I'd definitely ask about it at your next appt.

 

Have they determined the sex of the babies yet?
I am sure that is so confusing, glad you are getting extra monitoring either way!!
Take care and keep us posted!

 

On the first u/s they told me fraternal. But then we switched to a specialist, and they were absolutely sure they were ID, two sacs and a thin membrane. We started to have weekly u/s at about 14w to prevent TTTS, and we ended up with TTTS. Thank God, they got it on time, had surgery, and now the babies are OK, and now we're positive, they're IDs.

 

Yes indeed, we're having two girls! It is a bit confusing and it seems the more I read about it, the more confused I get. I guess I will let nature take its course and hold tight until they are here...it will be a nice little surprise either way.

 

Oh nooo...so glad to hear they are doing well!!! How far along were you when they spotted it? Ok, now I seriously won't complain about the frequent visits!

 

There is no way to tell if twins (of the same sex) are fraternal on ultrasound...

You can sometimes tell if they are, in fact, identical - if they share a sac, or if they share a placenta (that last one is only reliable on early ultrasound, because after a while, even if there were two placentas to start, they frequently grow into each other and look like one).

Fraternal twins will ALWAYS have two placentas and two amniotic sacs.... but something like 30% of identical twins also have two placentas and sacs, so it's no guarantee.

 

Yes...this. My OB would not say one way or the other in utero because they were both boys and he could not tell definitively if it was one placenta or two fused. Once they were born, my OB told me they were fraternal because they were clearly di/di (with the placentas fused). However, my boys are part of that percentage of di/di twins that are in fact ID so go figure.

 

I agree with the others, and I was always told that there's no way to tell 100% if they are identical until a blood test is done (other than boy/girl twins). My boys were in separate sacs with a thin wall between them and the placentas fused together. I also had regular ultrasounds to keep track of their growth and rule out TTTS.

 

And, just to further confuse the point, there is a percentage of b/g twins that are identical! Check it out!

I think it's all pretty amazing.

 

I was thinking about that while I was typing my response! But I didn't want anyone's head to explode!! :laughing:

 

The monozygotic, diamniotic, TTTS, donor and recipient, fraternal, no identical is an AWESOME way to deter the "they're not identical, are they?" questions. Confuse them into silence! He he.

 

At 22 weeks they found it. Weekly visits seemed odd and unusual at first, but I'm soo happy I had them after all!