Yesterday, we had the 20-week ultrasound for what, with luck, will be our second child. The news was good: fingers, toes, arms, legs, nose, heart, kidneys, etc., all present and accounted for in the usual quantities.
The first pregnancy was textbook normal, but we had a bit of a scare early on with this one in the form of a statistically abnormal nuchal translucency (NT). NT is computed as a ratio between measurements in an ultrasound, and large ratios are correlated to trisomic chromosomal abnormalities like Down Syndrome. We went ahead with a chorionic villus sampling (CVS), and the results showed no abnormalities. It was a long couple of weeks waiting for information after the NT result.
Looking at the prospect of testing, the amount of hard information available to the prospective parent is limited, even from a "genetic counselor" or physician. I asked about statistics and studies around NT and CVS, and the best that the caregiver could manage were the usual statistics — without even the false positive rate! I'm more interested in looking at the actual studies and statistics than most folks probably would be, but I don't think it's too much to ask people to give correct explanations and provide reference materials. Come to think of it, I'd like to see all scientific and medical research data available as open source (CC By-SA, perhaps?) and freely available on-line. (It looks like this is aligned with the mission of the Science Commons.)
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