It’s been a couple of years since I was pregnant with my first child and now I am pregnant with twins. With my first pregnancy I did no prenatal testing besides an Ashkenazi panel of genetic disease markers in my DNA. But this time around, I am doing much more testing. There are a few reasons for this: my multiple losses; my advanced maternal age (I crossed the formidable four-o barrier); and the fact that if there is an issue with one of the twins it would not just affect my husband and me but my son’s life as well.
So, I decided to move forward with the first trimester screenings. In hindsight, I wish I had done more research beforehand. The test (http://www.americanpregnancy.org/prenataltesting/firstscreen.html) takes three things into consideration, churns it through some sort of algorithm, and spits out two numbers. One number tells you your chances of having a baby with Down’s Syndrome and the other number tells you your chances for Trisomy 18. The three inputs for the magical algorithm include: NT measurement (the fluid level behind the babies’ neck via ultrasound), a blood test serum, and the mother’s age.
I knew going in that my results would be sketchy due to my age and the twins. What I did not realize was that the results were relatively meaningless, and thus, the test was pretty much useless. First, a screen does not tell you anything definitive, only a probability. Second, the blood tests are not accurate for multiples. The screen was developed for singletons and not for mothers carrying more that one baby. Third, no one tells you how the black box algorithm weighs each risk factor. Garbage in, garbage out. Since my fertility doctor in Austin told me I had the innards of a thirty-year-old, I asked my doctor here what my chances of a chromosomal abnormality would be if we took age out of the equation. He couldn’t give me an answer, although I found a website where I could plug different numbers in and play with the results.
So when the doctor entered the room all doom and gloom, telling me that I have to get more testing because I am considered high risk, all I could think was “No shit, Sherlock.” Very few women, if any, over 40 pass the test, so I can’t understand why they had me take it in the first place. According to some unreliable source I found on the Internet, anyone my age has a baseline probability of 1 in 38. Finally he conceded that the results should be taken with a grain of salt. Because of course, this isn’t a test you can pass. All it can give you is a probability, and its accuracy rate is 85% in finding abnormalities with a 5% false positive rate. The only thing going for this test is that it’s non-invasive. I guess if you’re under 40 and you’re satisfied with statistics, then this test will suffice.
My doctor suggested I go for a CVS, a test whereby they remove a bit of the placenta. But guess what? That is just a screen too with no definitive results, especially for twins! And it doesn’t even have the benefit of being non-invasive. So, I am going for a totally invasive amniocentesis I always planned to, and I am annoyed that my doctors bothered to administer the first trimester screening. What was the point? Did they do this to make more money or as a way to shield them from liability? Or did they just prescribe a test without thinking if it’s appropriate or consulting with me first?
In the future, I think they should discuss the pros and cons of each test before they start administering them. Any mother over 40 or mothers carrying multiples should pass Go and head straight to the amniocentesis if they believe that the invasive procedure and the peace of mind it brings warrants the risks. That would take the first trimester screening, the quad screening, and the CVS off the table, and save everyone time. For me, calculating my chances of a problem is pointless. Determining whether or not there actually is an issue prepares me to make informed decisions.