Vanishing twin syndrome??

[chicknik423]

Hi ladies!

I finally had my first appointment/dating ultrasound. Baby looks good and has a heart beat of around 178 bpm. After the ultrasound, the tech came back with a doctor, which I thought was odd, as a doctor had never talked with me after a dating ultrasound with my other pregnancies.

He said that everything looked good with the baby, but that there was something that he wanted to show me. He pulled up a pic on the monitor that showed 2 sacs-- one with the baby and another that was much smaller and completely empty. He said the pregnancy most likely started as a twin pregnancy, but that the second baby stopped developing at some point and would just be reabsorbed by my body. There was no tissue or anything visible in the sac, so I am assuming it stopped developing pretty early on (I'm 9w 2d right now).

In the moment, I was just surprised and relieved the one baby was doing well. I didn't have time to think of any questions to ask. The doctor made it sound like vanishing twin syndrome is pretty common and the surviving baby usually has absolutely no negative effects. Once I got home, however, I started researching, and came across a study that found that the surviving twin has a three-fold increased risk of having some type of chromosomal abnormality. Cue freakout.

Up until this point, I was going to skip any of the genetic screening/diagnostic tests, as I have done with prior pregnancies. However, now I'm spiraling and worried that there might be something wrong with baby, and I feel like I need to know. Apparently genetic screenings will most likely be inaccurate because it can pick up some genetic info from the "vanished" twin.

I'm not sure what I am looking for here, and I apologize for rambling. My next appointment isn't for another month, which I hope is still early enough for this to be discussed with the doctor and decisions regarding testing to be made. Does anyone have experience with vanishing twin syndrome?

[Argyle]

Hi there! I have two things to say.

First, even if you have triple the chance of problem X, if the original chance was extremely small, the odds are still very low. 3 times almost zero is still almost zero. So try to keep that in mind until you can talk to your doctor directly.

Second, I have no experience with vanishing twin syndrome, but I am a scientist and attended a research talk on the cell free fetal DNA test back when it was being developed. (This is the blood test that checks for generic disorders starting around 9 weeks). From my understanding of the basic science, unless your vanished twin is still actively releasing DNA--which it won't be if it's fully vanished--the test will be just as accurate for you as in a regular Singleton pregnancy. If it isn't fully vanished, then I do not know if it would still be releasing DNA.

I'm sorry for the stress, and hope you can feel more peaceful soon.

[Argyle]

There are also lots of reasons there would be a correlation between vanishing twin and chromosomal abnormality, without it being a cause. For example, older mothers are both more likely to have twins, and more likely to have children with chromosomal abilities. So it would show up as a correlation, but one doesn't cause the other.

Fwiw, Regular twins probably have a higher rate of chromosomal abnormality as well, but it's not like you'd hear you were having twins and go, oh no! Increased rate of abnormality! So if you can, don't worry.

[notelsie]

I’m here to offer hugs and support. It looks like you got some good advice above. I’m sorry you are going through this, I’m sure it’s very emotional and confusing <3

[chicknik423]

notelsie, thank you for the hugs and support-- much appreciated! I tend to over-research things and freak myself out much more than necessary, which is probably exactly what I am doing in this case. I love that I can come here to talk with you ladies, as I can't share this with anyone IRL since we haven't shared about our pregnancy just yet!

Argyle, you are wonderful and have made me feel much better-- thank you! Thinking about the chance of it happening in the way that you explained is much more comforting because, like you said, it is still a very small chance. Same goes for your explanation of correlation/causation. When it comes to the DNA being released, there appears to be NOTHING in the sac, so I would assume that there would no longer be any DNA being released. I'm still so conflicted as to whether or not I want to do any sort of genetic screening. I just turned 34, so I am on that borderline of being considered "advanced maternal age" (gosh, that makes me feel so old!).

[jillywilly]

I'm sorry for the added stress this is causing you. We transferred one embryo in our FET cycle. At 5w6d we saw one perfectly developing embryo with a flutter of a heartbeat, and one, much smaller with no detectable heartbeat. The doctor at that point told us he suspected a vanishing twin. He also said its relatively common, and when it happens, almost always leads to a normal, healthy singleton pregnancy. I'm at 9w2d now, and every subsequent scan has shown one beautiful little baby developing perfectly. We also did PGS testing prior to our transfer, so I'm at least one anecdote that it can happen when we know there were no chromosomal abnormalities, sometimes it just happens.

I also have a good friend who had a vanishing twin first pregnancy, and she has a happy, healthy five year old now.

[chicknik423]

jillywilly, thank you for sharing your experience. It quite comforting to hear that everything is going well for you. I am glad to hear that your doctor also mentioned that it is common and usually leads to a healthy pregnancy. I did read that we wouldn't be aware of most cases of this if we didn't have such early and advanced ultrasounds, which makes sense!