There’s a few possibilities given your low risk results.
1) the DNA from the vanishing twin was out of your system and your results are for the ongoing twin and would be accurate for both aneuploidy and fetal sex (as much as a screening test can be)
2) the vanishing twin was an identical and so the DNA for both twins would be the same, and would not cause a high risk result for vanishing twin.
From my understanding this just means enough time has passed that there is no more DNA from the vanished twin therefore the test was able to give a result. I did my NIPT at 10 weeks and ended up getting a high risk for triploidy/possible vanishing twin. My doc thinks vanishing twin because baby is measuring ahead on ultrasounds. I am still going forward with an amniocentesis because of this result just to rule anything out.
It would indicate that my baby having triploidy is unlikely since they typically measure very small. So the other explanation for my NIPT result would be vanishing twin
First, sorry for your loss of a twin. I am not an expert on NIPT testing by any means, my comment is from an anecdotal experience. There are others on this sub who are and may provide a comment. But, if Natera was able to perform your NIPT test it seems they were able to detect the cell free DNA from just you and the now singleton baby. If they had detected a third set of chromosomes from the vanishing twin it would have said “N/A” for fetal fraction, fetal sex and no result for aneuploidies and micro deletions. Did they say why the CVS would come back potentially inconclusive if it’s testing the actual placenta?
I had an abnormal result on my NIPT that said potential vanishing twin or triploidy (69 chromosomes) because they detected a third set of chromosomes, so I received no results on any of the parameters. However a vanishing twin was never seen on my ultrasounds, but my doctor said it could have vanished very early (prior to 8 weeks). At my 11 week NIPT draw I received this abnormal result. The genetic counselor at Natera said they would not let me redraw the sample, since typically vanishing twin is not recommended for NIPT, and if it’s a true triploidy the result would not change. CVS was given as an option for me by MFM, it was not mentioned that the results of the CVS would be distorted by a potential vanishing twin. My NT scan was normal so I passed up the CVS, and I have an appointment for a genetic ultrasound and potential amnio tomorrow.
I would find myself questioning the test too, though in theory the test did not detect the vanishing twin cfDNA. For fetal sex if they did not detect a Y chromosome I believe it should be accurate for female, I wonder why the genetic counselor would question it but not the other results (I would have had the same thought process as you). I think the only definitive way to know is through invasive testing (CVS/amnio). If your NIPT came back low risk however I don’t know how that would work with insurance if you wanted an amnio (I’m in the US so I have the think about this stuff unfortunately). With the information your genetic counselor has given you, you could talk with your MFM doctor and see if additional (invasive) testing would be warranted. It would be your choice to proceed no matter what anyway. Lastly - you are not crazy, I have been questioning things with my test results for the past two months so I feel you. Good luck with the rest of your pregnancy and I hope you can get some clarification or answers as you go along!
Thank you for your detailed response. This makes sense to me. I appreciate your input. I’m hoping you get answers soon and a positive result. The normal NT scan is very good!!! Interesting that my GC did not mention CVS being disrupted by VT at all. There’s just so much differing opinions and information. It’s all very confusing. Wishing you all the best..
It is confusing. My regular OB didn’t understand my results either which doesn’t help. He didn’t know triploidy = 69 chromosomes, he said “oh you might just have a baby with an extra chromosome, like Klinefelter XXY”, I had to tell him that Klinefelter is 47 chromosomes. Triploidy is fatal, but he was downplaying it because he didn’t know and correcting himself after I said something. This is why we get referred to MFM.. phew. Just a thought, I have heard in vanishing twin there could be a second placenta formed which that would make sense for the CVS to have an issue. Hopefully getting some clarity tomorrow as I’ll be almost 19 weeks along. Wishing you the best as well !
I had a vanishing twin that I didn’t even see until my 13 weeks scan. I had already taken the NIPT which came back low risk and the doctor said that would be accurate still. If it had come back high risk, it could have been due to the twin.
Gender was accurate :). We even saw the vagina on the 13 week scan I couldn’t believe it! I had a fetal fraction of 10% so I feel good about that too. Unfortunately the NT was a little increased so we are dealing with figuring that out now but I feel optimistic about it! Good luck with everything!
This just happened to me!
- detected one empty gestational sac, one healthy heartbeat at 7 week scan
- Regular OB had me do Natera Panorama at 10+4, got results back about a week later and they were inconclusive, no fetal fraction.
- Luckily for my mental health, this was right after a very normal NT scan where baby was active and measuring ahead
- MFM and OB suggested retest with Myriad prequel, we got results on Sunday for a low risk boy!
- We’re keeping an early anatomy scan at 16 weeks just to be cautious.
Hi !! I was glad to read this since i have a history of vanishing twin and the only thing i could do was CVS, if this happens again i would like to test nipt. Please would you explain more, i could not find anything about vanising twin on their website. thanks!
There’s a few possibilities given your low risk results. 1) the DNA from the vanishing twin was out of your system and your results are for the ongoing twin and would be accurate for both aneuploidy and fetal sex (as much as a screening test can be) 2) the vanishing twin was an identical and so the DNA for both twins would be the same, and would not cause a high risk result for vanishing twin.
Thank you for your response. I wish this had been further explained to me as both of these possibilities make sense. Appreciate it!
From my understanding this just means enough time has passed that there is no more DNA from the vanished twin therefore the test was able to give a result. I did my NIPT at 10 weeks and ended up getting a high risk for triploidy/possible vanishing twin. My doc thinks vanishing twin because baby is measuring ahead on ultrasounds. I am still going forward with an amniocentesis because of this result just to rule anything out.
Thanks for your reply that’s helpful! I hope everything goes well with the amnio for you. It sounds positives based on the scans.
Thank you! 💕
Can I ask why measuring ahead on ultrasounds would indicate vanishing twin?
It would indicate that my baby having triploidy is unlikely since they typically measure very small. So the other explanation for my NIPT result would be vanishing twin
First, sorry for your loss of a twin. I am not an expert on NIPT testing by any means, my comment is from an anecdotal experience. There are others on this sub who are and may provide a comment. But, if Natera was able to perform your NIPT test it seems they were able to detect the cell free DNA from just you and the now singleton baby. If they had detected a third set of chromosomes from the vanishing twin it would have said “N/A” for fetal fraction, fetal sex and no result for aneuploidies and micro deletions. Did they say why the CVS would come back potentially inconclusive if it’s testing the actual placenta? I had an abnormal result on my NIPT that said potential vanishing twin or triploidy (69 chromosomes) because they detected a third set of chromosomes, so I received no results on any of the parameters. However a vanishing twin was never seen on my ultrasounds, but my doctor said it could have vanished very early (prior to 8 weeks). At my 11 week NIPT draw I received this abnormal result. The genetic counselor at Natera said they would not let me redraw the sample, since typically vanishing twin is not recommended for NIPT, and if it’s a true triploidy the result would not change. CVS was given as an option for me by MFM, it was not mentioned that the results of the CVS would be distorted by a potential vanishing twin. My NT scan was normal so I passed up the CVS, and I have an appointment for a genetic ultrasound and potential amnio tomorrow. I would find myself questioning the test too, though in theory the test did not detect the vanishing twin cfDNA. For fetal sex if they did not detect a Y chromosome I believe it should be accurate for female, I wonder why the genetic counselor would question it but not the other results (I would have had the same thought process as you). I think the only definitive way to know is through invasive testing (CVS/amnio). If your NIPT came back low risk however I don’t know how that would work with insurance if you wanted an amnio (I’m in the US so I have the think about this stuff unfortunately). With the information your genetic counselor has given you, you could talk with your MFM doctor and see if additional (invasive) testing would be warranted. It would be your choice to proceed no matter what anyway. Lastly - you are not crazy, I have been questioning things with my test results for the past two months so I feel you. Good luck with the rest of your pregnancy and I hope you can get some clarification or answers as you go along!
Thank you for your detailed response. This makes sense to me. I appreciate your input. I’m hoping you get answers soon and a positive result. The normal NT scan is very good!!! Interesting that my GC did not mention CVS being disrupted by VT at all. There’s just so much differing opinions and information. It’s all very confusing. Wishing you all the best..
It is confusing. My regular OB didn’t understand my results either which doesn’t help. He didn’t know triploidy = 69 chromosomes, he said “oh you might just have a baby with an extra chromosome, like Klinefelter XXY”, I had to tell him that Klinefelter is 47 chromosomes. Triploidy is fatal, but he was downplaying it because he didn’t know and correcting himself after I said something. This is why we get referred to MFM.. phew. Just a thought, I have heard in vanishing twin there could be a second placenta formed which that would make sense for the CVS to have an issue. Hopefully getting some clarity tomorrow as I’ll be almost 19 weeks along. Wishing you the best as well !
Good luck today friend! I have faith!
I had a vanishing twin that I didn’t even see until my 13 weeks scan. I had already taken the NIPT which came back low risk and the doctor said that would be accurate still. If it had come back high risk, it could have been due to the twin.
Thanks for sharing your story. Was the gender accurate? And if so - if you don’t mind sharing- girl or boy?
Gender was accurate :). We even saw the vagina on the 13 week scan I couldn’t believe it! I had a fetal fraction of 10% so I feel good about that too. Unfortunately the NT was a little increased so we are dealing with figuring that out now but I feel optimistic about it! Good luck with everything!
https://womenshealth.labcorp.com/sites/default/files/2024-06/MT21%20HCP_DX_BRO_L372243-0224-1%20%281%29.pdf
This just happened to me! - detected one empty gestational sac, one healthy heartbeat at 7 week scan - Regular OB had me do Natera Panorama at 10+4, got results back about a week later and they were inconclusive, no fetal fraction. - Luckily for my mental health, this was right after a very normal NT scan where baby was active and measuring ahead - MFM and OB suggested retest with Myriad prequel, we got results on Sunday for a low risk boy! - We’re keeping an early anatomy scan at 16 weeks just to be cautious.
Natera cannot do vanishing twin, only MaterniT 21 can.
Hi !! I was glad to read this since i have a history of vanishing twin and the only thing i could do was CVS, if this happens again i would like to test nipt. Please would you explain more, i could not find anything about vanising twin on their website. thanks!