Monday, April 20, 2009

First Trimester Combined Screening results say we are High Risk

Screening test and Diagnostic tests. You'll receive lots of screening and testing results during the surrogacy process, pretty much the same as any other pregnancy. Screening tests are the first ones done, and they're the ones that scare you. Diagnostic tests are done later, and these give more accurate results. The main thing we were worried about was Downs Syndrome which is indicated by an increased calculated risk of trisomy 21. If you read the books, these screenings more often rasie unwarranted alarms (false positives) rather than quell fears. And they did for us too. Here's why.

The Double Marker screening was done around week 11 of our surrogate's pregnancy. It checked the Free Beta HCG, Serum by CLIA and PAPPA by CLIA. I don't know what that means either. But they take figures from these tests, the biological wife's age, and an ultrasound measurement of the nuchal translucency and run it through some predictive analytical software. Because it is predictive and not diagnostic, this is called a screening.

What I do know is that the email and scanned results came back showing the pregnancy was high risk, that "the calculated risk for Trisomy 21 is above the cut off which represents an increased risk." This was enough for my wife to start crying and pass me the paperwork.

This is what you have to realize: any risk calculated at higher than 1 in 250 is considered an increased risk. For us, the calculation was 1 in 107, which by that definition is an increased risk. But what that really means is that 1 in 107 births like ours will have Downs syndrome, which is less than 1 percent. That's why this test raises so many false fears.

More interesting is that if you only look at my wife's age, all the charts show a risk of 1 in 50. So, although the risk is "high" by the arbitrary definition of more than 1 in 250, when looking at not just her age, but also the additional medical information above, the odds had actually moved in our favor from 1 in 50 to 1 in 107. That was good news. And my wife was relieved.

The Amniocentesis test is the diagnostic test. Those provide more definitive results. I'll post on those separately.

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