June 16, 2003
permalink The lovely 13 week scan

Well it's 10 weeks now since I had this scan done. It was wonderful. At 13 weeks the baby is small enough to fit nicely into the screen of your ultrasound monitor. Tiny and yet everything seems to be already formed and so it is just overwhelming.

I think we were still expecting a bit of a blob, but we saw a wee complete human being waving its hands and feet about, having a drink and just lazing about in it's luxury abdominal hammock.

I thought the baby looked a bit like a swami doing some fairly serious yoga as it lifted its leg up behind it's head. "Oh the baby's just doing that because it can." the sonographer said, smiling. Very cute.

Such a relief and an amazement to see all those little fingers and toes so perfectly formed and to hear the words, "everything looks great".

My partner I think was even more excited than I was and he said afterwards that it's hard being the male. It all seems a bit abstract, distant in a way. I think sometimes he'd like to be the one pregnant even if it meant having to put up with the morning sickness and the hard work of birth, just to be able to feel it all from the inside and connect with his little baby. Anyhow, the 13 week scan made him feel really close to the baby he said. He got a real buzz out of it.

The sonographer we had was brilliant too. Very reassuring and very knowledgable. She carefully explained all the measurements and readings to me afterwards and outlined what the Nuchal Fold test had shown. The statistics and the accuracy of the test for predicting Down Syndrome. After I showed frustration at the only 80% accuracy of the test, she said to me,"if you had got the first trimester blood screening done (PAAP-A) at the same time we could lift our accuracy to 90-95%." I raced out and got it done. It was an incredibly stormy afternoon, I had to travel to the other side of town, and my doctor sent me first to the wrong pathology lab to have the test done, so it was quite a feat to get it done at all, especially as my window of opportunity to get the test done was very small. But it was well worth it! :-)

Nuchal Fold Test

The nuchal fold test done at an ultrasound at 11-13 weeks measures the thickness of the baby's neck and gives a risk factor for Down Syndrome. With the nuchal fold test alone. the accuracy of predicting Down Syndrome is 80%. That is, of every 100 babies born with Down Syndrome, 20 would not have been picked up by the test.

If you have a first trimester blood screening (PAAP-A test) done at the same time (needs to be done before 13 weeks) they combine this result with the nuchal fold test to give you a new risk factor which has 90-95% accuracy. ** see note below

I wasn't told about it before the nuchal fold test as it is not considered 'routine' yet in the state where I live. I was a bit cranky about this. The fantastic woman who did my 13 week nuchal/ultrasound only told me about it after I started asking a zillion questions about abnormalities and whether an amnio or cvs might be worth it.

** Note: Just over two years later (mid 2005) when I was pregnant with my second child, I found that most doctors were not using the PAAP-A first trimester blood screening for women with diabetes as it was found to result in too many false positives.

The combined tests put my chance of having a baby with Down Syndrome at 1:2030. Based on my age alone the chance of having a baby with Down Syndrome is around 1:240.

Posted by patton at June 16, 2003 10:55 AM
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