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UPDATE: Vanishing twin misinterpreted as yolk sac?

post #1 of 15
Thread Starter 
Hi all,
You may remember me from a few weeks ago - I was one of the many who were *convinced* I was carrying twins but found out otherwise at 7w5d. I've been having a really hard time dealing with this revelation since it's made me doubt my own instincts and feel that anything spiritual is probably foolishness. Anyway, I'm digging out of that by myself, slowly. My question for you all is whether you've heard or experienced an ultrasound diagnosis that missed the second baby because he/she was identified as the larger baby's yolk sac. During my very quick abdominal ultrasound we saw a smaller, solid structure sitting a ways off up by the living baby's head (within the same sac). We also clearly saw the living baby's umbilical cord leading in the other direction away from the baby's feet to the placenta. The family practice doctor (not a radiologist), declared the smaller structure the yolk sac, but I'm suspicious. According to my embryology training when I was in med school (I'm a medical illustrator), the yolk sac at this stage is wrapped up with the umbilical cord structures and if visible still should be seen up by the umbilical/placental insertion. I remember the "yolk sac" as a solid structure, not the hollow ball that it should have been (but maybe I'm misremembering). The still photo I have shows it as a solid ball.

Obviously there's a lot of psychology here since if I can believe that there was a second baby it would restore my faith in my inner voice. But I also don't want to be just pulling the wool over my eyes again and again. What would you do?
post #2 of 15
At 7w4d my ultrasound showed an open circle for each baby in what appeared to be a single sac. There is a possibility that what you saw was a second baby esp if they were monoamniotic and shared a yoke sac (as mono/mono twins do). I don't think that it's unreasonable to believe that may have happened. If you want a pic to compare I can send you mine. The yokes were very clearly visable as were the fetal poles.

ETA, The cord you may have seen may have also been the membrane seperating the two and is a further indicator that you may have or have had a twin.
post #3 of 15
Thread Starter 
Thank you, fyrebloom, I truly appreciate the time you took to respond. I would love to see your 7w4d ultrasound for comparison. There are a couple things that confuse me about your thoughts - one, my understanding is that twins never share one yolk sac unless they are conjoined in that particular way. The yolk sac is actually a small structure that is part of the embryo's future intestines/gut tube and spends some time outside the main body, then is enclosed in the umbilical cord, then comes back into the abdomen when there's enough room for it after the body grows enough to make way for their HUGE liver. This is why in some cases we see intestines left outside the belly button, because that's where they hang out in the embryonic period. That was probably TMI. I think you're probably thinking of the amniotic sac and chorionic sacs which surround the whole baby. What I'm talking about is a yolk sac . . . I'll take a photo of it and make some notes on it to share.

7w5d Ultrasound showing mysterious yolk sac/vanishing twin

The other thing is that I'm certain the structure the doc identified as an umbilical cord really is umbilical cord and not part of the membranes. You can see in the ultrasound above that it's pretty clearly a solid, thicker line coming from the baby to the placenta.

A couple things to note about the ultrasound image: one is that the "yolk sac" is not round, it's oblong like the shape of an embryo. It's also not hollow, and my Dh does not remember seeing it look hollow during the live ultrasound, either. Also we never saw anything connecting the "yolk sac" to the baby or umbilical cord, it was just there on its own, over by the viable baby's head.

What do you think?
post #4 of 15
I had a 6wk trans vag us and 8wk trans vag us with this pregnancy due to a miscarriage the previous month before this pregnancy. On both ultra sounds the doctor missed the second twin. Needless to say at my 18 wk ultra sound we where very shocked to see two babies. I don't know if this helps any but, they do miss them sometimes.
post #5 of 15
No I did mean the yolk sac.


Mono/mono twins share a yolk as well as the amnion and chorion because the baby actually splits AFTER all structures have formed. The yolk forms at the same time as the amnion.

Here is a pic of my ultrasound.

Note how both babies look to be in the same sac (they are monochoriatic). You'll also notice a light line in the background near twin b. That is most likely the membrane and not a cord.

I think you are absolutely right. That does not look like a yolk sac at all and I also think that is a twin. At this early stage it may be hard to determine if there is a twin. If they assumed that that was a yolk then they would not try to get a bigger picture of the other fetal pole. I agree that that is probally is a cord as the membrane would be very thin and hard to see. Also I don't see any yolk at all, but it may have been absorbed already. I don't think that they are mono/mono.... I think that they are mono/di twins and either you still have them both and didn't get a good pic of B or one was in the process of being absorbed.
post #6 of 15
Please don't doubt yourself! Trusting your body and your inner voice is one of the most powerful intuitions as a woman! There are so many reasons that you might be feeling a second spirit within you. they may have missed a baby, you may be carrying a sacond spirit baby for any number of reasons. My midwife had 2 fetal heartbeats throughout her entire pregnancy including during labor. There were two other midwifes and her husband who is an MD for pete's sake. At the time of delivery, she delivered one very large baby. Her husband waited for another and alas, one baby was all that there was meant to be. Does that mean that there was not another spirit also? I don't think so. You are talking about your spiritual self....you need to have faith that allowing your spirit to go where it needs to, opens you up to more than flesh and blood....don't lose faith....

post #7 of 15
Thread Starter 
Just an update for anyone wondering about this. I went in for a ultrasound yesterday to check on the baby after some intense cramping and light spotting on Sunday (I was dehydrated - 11 weeks). It was quite clear that there is only one baby in there, who is growing remarkably fast. There was a small dark area just next to the baby's sac that looked like it could have been a second sac getting reabsorbed, but who knows. We saw the distinctive yolk sac up by the placenta and definitely hollow and round. I now feel fairly convinced that there was a second baby earlier who didn't make it. I wonder a bit if the second baby's placenta is contributing to the rapid growth of the surviving baby? He/she was measuring right on at 7w5d and is now measuring 12w6d at 11w3d (10 days further ahead). I know ultrasound dating gets less and less accurate as you get further along and baby's begin their unique growth patterns, but is 11.5 weeks at that point already?

Well, I'm celebrating this baby finally now - she/he was so lively while we watched (probably saying "get these pulses OFF me ) Lots of hands up by face, possible thumb-sucking, little wiggles and rolls from side to side. Also she/he laid in a particular spot for a while against one of my uterine blood vessels so that his/her head was dramatically bobbing with my heartbeat. And, after I finally got to empty my bladder we came back and he/she was doing trampoline jumps every few seconds. I also felt movement for the first time on Tuesday.

Thank you for the hugs and support. I truly appreciate the time you've taken and the care you've shown.
post #8 of 15
While twins are a very special blessing, I have no doubt that you will find all the joy you could ever want in your beautiful singleton baby. There is, in my view, no need to doubt your early intuitions about your pregnancy. If nothing else, perhaps your child will have a special spirit companion to go through life with her/him.

I don't know much about vanishing twins, but is it possible that your cramping and spotting were related to that?

Congratulations on your pregnancy!
post #9 of 15
Hugs to you. I had a vanishing twin with my first pregnancy. Our dd born from the pregnancy is so very special and I am comforted that she has "someone" watching over her. She was born with a shock of white hair and can still be seen at almost 3yrs old. My dh calls it her twin

post #10 of 15
Here is a rather detailed article on the topic of vanishing twins:
post #11 of 15
Thread Starter 
Thank you, mommymaemae and juju's mom for your perspective on a surviving twin's spiritual sibling. I really appreciate that, and hadn't thought of it in that way. khrys, that article was very interesting. I had read that 1 in 8 pregnancies are guessed to begin as multiples, and noticed the rate of suspected naturally-occurring multiples is 12% there (the same). This is the first concrete reference I've seen of this, so I'm grateful to have read it because it helps me feel less delusional believing there were two at first. I'll be interested to see the placenta after I birth, to see if there are any signs of the lost baby there. We'll definitely be making a placenta print, doing a lotus birth, and planting the placenta under a tree (or maybe two?), since that may be all we'll ever have physically of this lost child. (That makes me wish I had asked for the tissue back from my very first pregnancy, when I had an in-office procedure to remove it after my loss .) Anyway, I don't want to strip that last physical connection away from my surviving child so quickly after birth, so we'll allow nature to take its course. I was always uncomfortable with cord-cutting - as was my Dh who did it - even after the pulsing had stopped and the placenta was delivered. Lotus birth makes even more sense in the case of a vanishing twin, IMO.

Take care all. Thanks for letting me write this out and process it with your support.
post #12 of 15
my sister recently told me that her 8 yr old daughter was a twin. She showed me the ultrasound pictues and theres NO DOUBT, defintley twins! Very sadly the other baby didnt make it - "vanishing twin" situation. one thing i am learning is that, once a twin mama, always a twin mama sounds like you are a twin mama to me! You hold one in your womb, and one in your heart.

Blessings your way mama. Dont doubt yourself!!!
post #13 of 15
I don't know why I came onto this forum, I don't have multiples. But I'm glad I did...

My second pregnancy seemed to start out different...I was "poochy" at only 5 weeks, definitely showing at 9 weeks. Hmm... LOTS of twins in the family.

So I go in at 10weeks for my first appt and the dr also says Hmm...you're awfully big, let's do an ultrasound. The first thing he says is "oh honey, you're not 10 weeks, you're only about 6...there's a yolk sak still" And sure enough, there's a peanut and a very noticeable round ball not far from the baby. I say that I'm positive about my dates. He takes measurements and the baby measures 10 weeks exactly. So he says "huh...oh well, guess your yolk sak hung around a while longer than usual."

I had a nagging feeling and just couldn't get over it. I called my mom who said to research twins of different gestational ages, thinking maybe I had ovulated after conception and also conceived that month. I read up on it and although it's rare, it does happen (more often in animals like cats and dogs) I also read about vanishing twin syndrome and just couldn't shake the feeling.

Next appt there was only one baby. My pregnancy went to term and I delivered a healthy baby boy. I asked them to check the placenta carefully, but nothing was found.

So I don't know... I honestly thought I had twins in the beginning...I guess I'll never know for sure.
post #14 of 15
I had an ultrasound at 8 weeks and they only saw one baby, then at another ultrasound at 14 weeks they finally saw two.
post #15 of 15
Originally Posted by gemelos View Post
I had an ultrasound at 8 weeks and they only saw one baby, then at another ultrasound at 14 weeks they finally saw two.
I met a woman last weekend with 5 girls...2 sets of twins. She said they missed the second baby in her early ultrasound in BOTH of her pregnancies!! :
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