NIPT, The IONA test
Morning and time for another trip to the hospital. Only one day after the phone call with the news that my risk for having a baby with trisomy 21 or Down’s syndrome was 1 in 47. Today I had the NIPT blood test. This stands for Non Invasive Prenatal Testing. The particular test I having done is the IONA test which is run by Premaitha health.
There are many other brands of this test but they are all basically the same. It is a simple blood test, like any other they don’t need to take it from anywhere special just your standard vein in your arm. The blood is placed in a special vial for analysis that preserves the DNA that the lab look at.
When you become pregnant the placenta takes over the job of nursing your baby and to do this it allows nutrients to pass from the mothers blood stream into the baby’s blood stream. When this happens some of the baby’s DNA fragments get into the mothers blood stream and these fragments are what the test looks for. This is called Placental free DNA. The NIPT tests can distinguish between the mother’s DNA fragments and the DNA of the baby and then they can look at that DNA in detail. The NIPT test specifically looks for Trisomies 21 (Down’s syndrome), 18 (Edwards syndrome) and 13 (Patau syndrome). The IONA test that I have had comes with an accuracy of 99% for all three trisomies. The results, when the come back are shown as a risk factor so are shown in either a percentage chance or a ratio eg 1 in 100000. This test although very accurate cannot be described as diagnostic as there is a rare chance of something called confined placental mosaicism. This is very rare but does happen. This occurs when after fertilisation the cells start to split to form the blastocyst. Some of these cells for the baby and some form the placenta. In confined placental mosaicism the cells don’t split correctly and the placental cells get the extra chromosome but the babies cells have the normal number of chromosomes. Therefore when the DNA fragments mix with the mothers blood the trisomy DNA from the Placenta is what is detected by the blood test. This only occurs in 1 to 2 % of trisomy pregnancies which although rare is why the NIPT test cannot be considered diagnostic. So there is the science behind it which I hope I have explained well enough to give you a good understanding of what happens after your blood has left your arm.
So I sat in the waiting room in the same chair I was sat in just a few days ago waiting for my name to be called. One of the nurses from the screening department came out and called me into one of the side rooms. We had a quick chat about how I’m feeling. And then she gets out the paper work with my results from the combined test to show me.
My results for the nucal translucency measurement and the PAPPA hormone are within normal levels but my HCG levels are raised and around three times the normal range. This is why I have been feeling so ill. its not just normal morning sickness my hormone levels are making me feel three times as sick as I should do. Well thats how I interpreted that result. This was my red flag. So all these numbers combined give me a risk factor of 1 in 47 chance of Down’s syndrome. Scientists are still trying to find out exactly why you get high HCG levels with babies with Down’s syndrome but it is now a well know marker that is tested for. The midwife is really lovely and explains things really well. She doesn’t pussy foot around the subject just gives me the info plain and clear and makes sure I understand everything. Because the IONA test is not available on the NHS yet I have to read through and sign a consent form and answer a few demographic questions that help in the research and development of the test. I also have to fill in a payment form as it is not free its costing me £300, although she tells me that the money wont be taken until they have a result. She explains to me that the results will come back in around 5 working days but to phone them if I haven’t heard anything after a week. She then explains to me how the results will come back and what they will mean. But as I have spent half the previous day googling the test I am well informed as to what to expect. Then its time for the blood to be taken. She did my right arm this time as I am a bit bruised still from the previous test a few days ago in my left arm. Its fine, it doesn’t really hurt and I’m not squeamish about blood tests. The whole appointment takes around 10 minutes. So I went back to work. Feeling little more positive as there is only one thing raised and not all three so I’m confident that everything is going to be fine and that my 98% chance of winning the baby lottery is pretty good odds.