One placenta?

Just had my 20 week u/s. The tech told me they only saw one placenta. I asked if it was two that were fused and they said they were "pretty sure" that it was 1. If that is the case, does that mean I have ID twins? I should know this from before...but I don't. I know they are in two separate sacks, so is that what they call mono/di twins?

Thanks!

 

That's right, one placenta, two sacs does mean mono-di, and that means identical!

As I understand it, the way techs can tell one placenta / fused placenta, is based on at least two things - the thickness of the membrane between the babes. di-di is thicker, because the membrane is made up of more layers - the two sac walls and the two chronion walls, vs mono-di where the membrane is the two sac walls, with the chroion all around both. Also, where the separating membrane hits the placenta is different - with di-di fused, the connection is more of a wide delta, where mono-di is more of a T shape. If that makes sense.

It is a little harder to tell the difference as the weeks go on. At 20 weeks the techs are probably right about your babes being mono-di, but it's not 100%. There's still a chance yours could be di-di, and therefore possibly fraternal. But assuming your techs are right, identical they are! Very exciting! Congrats!

 

Yes, one placenta + two amniotic sacs = mono/di identical twins. They told me mine had only one placenta at our first trimester screening around 14 weeks, and pointed out how the separating membrane looks different than it would if it was two placentas that were fused or were very close together. Has your doctor mentioned anything different about how they are planning to monitor you or anything? I can't speak for anyone else but once they determined I had mono/di twins they scheduled me for biweekly ultrasounds to monitor for TTTS and put me on a high protein diet. (FWIW, all the scans look great so far and I'm at 25 weeks now.)

 

My OB originally asked me to ask the tech about the choronicity of the membrane during the u/s b/c he said the membrane separating the two looks really thin. I have not yet had a f/u appointment w/him to discuss it further. I thought mono/di twins had less risk for TTTS? Why high protein diet? All I crave is starches...id have to revisit my diet quite a bit! Wow I don't really know what to think, I figure I just won't know until they are born. I am not finding out genders but based on the tech thinking it was one placenta I must be getting two of one gender...had it been g/b they would not be questioning the placenta...

 

I have read high protein is just good for pregnancy in general. I just started the Brewer Diet for twin pregnancy and although I'm normally a big sugars/starches person even if they're whole grains, eating all the protein is really helping me crave fewer carbs. http://www.drbrewerpregnancydiet.com/id32.html is the site if you're interested.

 

Well, what my doctor told me (again, I'm not a doctor and I don't know what other doctors would say) is that TTTS is possible any time that there is a single placenta. It's related to blood flow which comes from the placenta, not to the amniotic sac. There is no risk of TTTS if you have two placentas because in that case each baby has their own blood supply. He told me that there is no rigorously proven way to prevent TTTS, but that there is anecdotal evidence and some scientific evidence that a high protein diet (>= 175g protein/day) can help prevent it, and gave me a copy of an article about it. In any case, all I can tell you is that he told me to eat 175g protein in about 3500 calories/day and they check the babies' fluid levels, sizes, and blood flow every two weeks by u/s. They also put me on a bunch of vitamins/minerals in addition to my prenatal vitamin (D, E, folic acid, magnesium, and zinc). I think each doctor may have a slightly different treatment protocol though so def. check with your own.

I will admit it freaked me out at first because I was still having morning sickness when we found out about this and there was no way in hell I was going to be able to eat 175g of protein or 3500 calories, but since the nausea has gone away I've been on track with it and all the scans have been good. I eat a lot of starches and carbs too though -- really I just eat a massive quantity of food all day long. :lol:

 

Cottage cheese is one of the only ways I can get enough protein in. I eat a ton all day long, too. At least supposedly if you gain wt on healthy foods during PG it's easy to lose. I don't know. I didn't have any problems losing wt after DD's birth, just feel huge now.
I hope you don't have to deal with TTTS but I'd look into the high protein anyway, even if there isn't a ton of evidence for it preventing, it would probably be good for babies' growth regardless.

 

yeah I have been reading a few things here and there. I am anxious for my f/u appointment to see what my OB will say...but right now I seriously eat protein in the form of meat/eggs/cheese maybe 1x a week...otherwise it is a lot of carb city for me! So maybe I will make some adjustments...

 

Did your earliest ultrasound show one "black hole" or two? The earlier the ultrasound is, the easier it is to tell if it's one or 2 placentas. Either way, CONGRATS!

 

I had another u/s where the tech again confirmed it appears to just be one placenta and they have said these are "mono-di" twins. I have not yet seem my MD b/c it is a week where I meet with the NP/PA. I actually spoke to both of them and neither will say conclusively if that means they are ID. They said the only way you know "for sure" is when they are mono/mono. So does that mean I just won't find out until they are born? Is it possible fraternal twins would share one placenta? I am thinking they are just not educated on the topic, but maybe there is still the case there are two fused placentas and u/s is not an accurate indicator? I don't know why I just would like to know.

 

What appears to be one placenta in an ultrasound *can* be two that fused together very early. Did they have a hard time spotting your membrane? I remember that they did? I'm willing to put money on them being ID.

Despite the stress and worry over finding the (very thin!) membrane and the TTTS monitoring, they had us questioning by the end, too. Talk to your doctor at delivery about checking the placenta. They probably won't do it unless you ask and they certainly won't tell you the results unless you ask, but that's one conclusive test.

We have ONE known case on TS of fraternal twins with one placenta and she just shared it with us last week. It's very, very unlikely. Go check her post out in the Twinstuff Club- it's titled "they said it couldn't happen", I think.

 

There are only two ways to get a single placenta: either you have identical twins, or there were two placentas to start with and they fused together. If there were two placentas originally, they could still be identical! It just depends on when the splitting happened. The way they tell the difference between a single placenta and fused placentas on ultrasound is by looking at the dividing membrane between the amniotic sacs. (See wikipedia: http://en.wikipedia.org/wiki/Monochorionic_twins but don't freak yourself out reading about the complications). Typically the earlier in pregnancy they look at it the more accurate a picture they get. It is statistically more likely that if they see one placenta on the u/s that they are identical; fused placentas are less common.

I wonder if it would be useful to have people on this forum share u/s photos. I know that in my u/s photos (mono/di) the membrane looks very different than the photos that were posted by the person with fused placentas (sorry, forgot your name!).