Discerning twin type in utero- tech changing her mind in second tri?

lupineaura · December 2014

Hi everyone, I am so thankful for your expertise. I had a somewhat confusing scan today, and research on the Internet has not really helped that much. From the beginning of my pregnancy, they were fairly sure that my twins were di/di fraternal. Not only were my ovaries quite stimulated on fertility drugs, but during previous scans the ultrasound tech commented on the thickness of the membrane separating the babies, and gave her opinion that they were almost certainly fraternal. At my 12 week scan, she told me both my placentas were anterior so I know she saw them at that time. There was no mention of the possibility of a single placenta

I had another ultrasound today at 16 weeks. As the scan progressed the tech started getting more and more convinced that the twins are probably identical. She pointed out that the top of the membrane had more of a T-shape than a V shape. Also, she and the doctor took a look at the placenta and now they're saying they cannot tell if it's two placentas that are butting up against each other or if the babies share a placenta. The plan is for me to go to MFM for my anatomy scan at 21 weeks. The doctor is curious what they think about the twin type/placental issue as well.

After my Internet research, it seems like the separation (lack thereof) of the placentas should've been determined between 11 to 14 weeks. I can't really tell, but it seems like this is more difficult to tell during the second trimester? I may call my doctors office tomorrow to ask what the 12 week scan showed in terms of a single or double placenta. Of course I'm also a little bit worried if they share a placenta. It seems like I should be monitored about every two weeks instead of every four weeks if that's the case? I'm wondering if I should ask to go to the MFM sooner for second opinion.

The good news is the twins are basically the same size and the tech sees no sign of TTS.

Opinions? Advice? Any similar experiences? TIA!

Edited to try to fix mobile formatting issues

carrotcake06 · December 2014

Placentas can fuse. Did she tell you what the sexes of the babies were?

Do you have any early u/s pics you can show us? It's a lot harder to tell di/di or mono/di the farther you get in your pregnancy.

My guess, without seeing early u/s pics, is that they're di/di.

Bigboneded · December 2014

I was told di/di and then MFM asked why I thought that?... "Because I was told there are two placentas?" It has gotten more difficult for them to see membrane separation as the pregnancy has progressed. A second opinion never hurts, and I agree with you if they are going to say now you are mono/di, I would insist on the closer monitoring. But if there were 2 distinct placentas to start, they are probably just bigger and its more difficult to differentiate.... GL! :-)

lupineaura · December 2014

Thank you both! I'll look at my earlier ultrasound pictures, but I don't recall seeing the placentas (the tech printed out the "cute" pics, haha). If I find a good one I'll scan it in.

*edit* Sorry, forgot to answer the question about the sexes. She is pretty sure Baby A is a girl, but not sure about Baby B. She was leaning towards girl, but only gave me 60/40 odds. Then I think she was thinking girl because she was getting convinced they are identical

carrotcake06 · December 2014

You wouldn't necessarily see placentas in the early pics, you're looking for the number of "black holes". If you see one with two babies in it, then likely mono/di. If you see two, then di/di.

4legsRbest · December 2014

My boys had a fused anterior placenta. We weren't sure if they were di/di until they were born (we were pretty positive because we transferred two) but they couldn't look more different. We had the option to send the placenta off for testing but it was obvious from the second they were born so we never did.

RayRay007 · December 2014

At my first ultrasound at eight weeks the twins were clearly di/di. At my first OB/MFM appointment at 12 weeks I first saw a resident who couldn't tell. She couldn't quite see the membrane and the placenta looked like one. When the MFM came in to have a look she pointed out the membrane and the division in the placenta. Hopefully you get more answers from the MFM.

SV917 · December 2014

My twins are di/di (boy/girl so definitely not identical). At the 12 week scan the tech only saw one placenta. I do not think it's uncommon for the placentas of di/di twins to fuse together.

lupineaura · December 2014

Thank you all! Some updates:

1) I called the office and the doctor wasn't in, but the woman who answered the phone looked at the report from my 12 week scan and noted they were referred to as "di/di twins." There was no specific note about the placenta.

2) I heard back from my doctor via text (he is pretty great that way; he says to text if he isn't in the office) and he said, "We will really know at 20 weeks with MFM. No reason to worry for now."

Do you think I should push for an earlier referral? I did ask if I should go in my initial question, and that was his response. I should note I do really like and trust my doctor; he also delivered my daughter (my only reservation is he is not a MFM).

GirPipley · December 2014

This is interesting timing b/c I have the same things going on. At my first few scans, I was told Di/Di b/c there were two sacs, and two yolks.

I had my NT scan on Wednesday, and this was the first time they were able to see the placenta and there is only one. They said they could have fused already, but there was no sign of fusing as it is very smooth. There is also no twin peak sign at all, and my membrane is there, but "pretty thin for di/di". A tech, an OB, and a genealogist all took a look, and they all think they are mo/di.

They turned on the 4D for a minute to try to see if they could get a peak at the sex, and the Dr said he is "pretty sure he got the sex" (We are team green so we didn't ask.)

So now we are being told we might have mo/di twins. Either way, I'm seeing a MFM next week, so maybe I'll know more then.

ksgsmu · December 2014

I would push for an earlier MFM appointment personally. My twins membranes were super easy to see at earlier appointments then they got more difficult so my MFM studied my early sonograms to make sure at one point.

ktibbits1 · December 2014

My placentas fused as well. I didn't even know that was a thing until after I delivered! I'd say if you feel more comfortable seeing the MFM earlier than go ahead and ask for the referral. I never saw one at all with my di/di twins but wish I did...

macchiatto · December 2014

My di/di twins' placentas fused as well. I agree it might be worth it to see the MFM sooner. My understanding is that earlier u/s are more accurate in determining twin type but I'm not sure. I didn't have a u/s until 12w and then every 4w after that. I was told at the 12w u/s that they were clearly di/di.

lupineaura · December 2014

Thanks again all! Unfortunately I couldn't even get an AS at the MFM until the last week in Jan when I'm 22.5 weeks. However, this morning someone from that office called and they are going to squeeze me in for an additional early scan tomorrow morning! I guess they wanted to be sure about the placenta issue as well- I'm so glad I'll get to see the MFM early. Thank you all for encouraging me to advocate for myself. I'll update you tomorrow.

pea-kay · December 2014

It's definitely easier to tell at earlier ultrasounds. I have some helpful graphics on my blog (link in sig to the page in question.)

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Discerning twin type in utero- tech changing her mind in second tri?

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