20 week ultrasound abnormal

I went for my 20 week ultrasound at 20w 4d.  I was told that the baby's nuchal fold was 5.3 mm which my doctor said was thick.

I had the NT scan at 12w 4d along with the blood work and the scan was within the normal range and the blood work came back fine.

I was also told that the tech couldn't see the aortic arch.

My question is why would the first tests be normal and now 8 weeks later be abnormal?

Also could the aortic arch and nuchal fold issues be related?

[Dragon1973]

Hi ktozzi1130,

Just wanted to say I read your post, and yes the two items can be related if they suspect that your baby has Down syndrome.  The NT test helps doctors determine if your odds will be increased for Down syndrome or other chromosomal abnormalities.  Coupled together with the heart concern, (as 40-60% of babies born with Down syndrome have congenital heart defects) may increase your odds or risk factors for Ds.  Now, having said that, these two items may also just be what we call "soft markers" which are also used to determine Ds, or can simply be nothing at all.  Please know that having a thick measurement for NT folds alone doesn't necessarily mean your baby is at increased odds for Ds.  Also the aortic arch also doesn't mean Ds, simply because congenital heart defects are the number one birth defect affecting children everywhere, of all types.  My question to you is, are you having any other prenatal testing if your doctor discusses your odds with you?  Did your doctor tell your your odds before these results, and was it markedly different after?  When I had my NT scan for my son, it actually came back totally normal, and they did not detect any heart defects until after he was born, yet he was confirmed with Ds via Amniocentesis.  So you can see that even if the results are not out of whack, the result can be something totally surprising.  I would encourage you to message me directly if you have other questions, but I also do not want you to worry unnecessarily.  I know how stressful it is to have results that are out of the ordinary but often times these are just risk assessments, and do not guarantee that anything is wrong with your baby.
Please keep me posted, and let me know if I can help you with anything at all.  
Sincerely,
Sandi (Dragon1973)
MedHelp Down syndrome Community Leader
& Ds Group Forum Founder/Moderator