The test is accurate in what it is measuring. The NT scan measures the skin at baby's neck and the blood test measures certain chemicals in the blood.
The combination of the results give you a risk figure. This figure is also accurate. If the risk figure for DS is 1/250 it is saying that of 250 women who have those results, one woman will have be carrying a child with DS.
It is how we understand and interpret the results that leads people to say the screen is inaccurate. Some people will see 1/250 as extremely high, whereas others will see it as a low risk.
Before having the 1st trimester screen, the doctor should explain how the results work, and that the results are not definitive, just that they can tell you if you have a higher chance of carrying a child with a chromosomal variation. It should also be discussed what you think you might do / feel if the results came back as high risk, and the implications and risks associated with further testing.
The first trimester screen has come to be seen as routine, something that everyone should have. Everyone wants to see a low risk come back, but it is also important to think about what you might do if the results are not what you thought they might be.
The stated risk of miscarriage following CVS is 1/100, and in amnio is 1/200. It's a lot of maths and figures, but something that must also be considered when deciding whether you would have follow up testing.
Officially, they are not supposed to release the results of the blood test and NT scan separately because it can cause unneccessary stress. The risk figure is a combination of maternal age, NT measurement and the blood tests. Having all results together give you the most accurate information.
hey hun, just wanted to come back in and tell u i got my blood test results today, and theyve decreased my risk to 1 in 1090 - so now considered low risk.
Your younger than i am, so that will work in your favour as well. Im sure all will be right. keep us posted!
I wouldn't worry about that measurement. I was told under 3 was fine. DD was 3.8mm but my BT was really good. Our risk was 1 in 119 and we had CVS done and all was fine. DD is perfectly healthy and no abnormalities.
A lady I worked with got 1 in 7 chance and also had CVS only to have healthy baby.
I really wouldn't be worrying especially since you do not have your BT work back. Not sure why your OB wouldn't be happy with that reading.
Mine was 2.6 I think but combined with my BT results my risk was very low - somewhere around 1:9000. So dont panic until you are told too. I was worried to but all for nothing!
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