First Trimester Screening – The Need to Know Basis

For sure you have heard about first trimester screening before, but it is also important to fully understand what it refers to. If you understand the concept most probably you will be less anxious about the results. The screening tests don’t refer only to the blood tests, but some other factors as well.

How is the screening in the first trimester done?

If you are going to have a screening, this starts with drawing blood, which takes about 5-10 minutes. This sample is sent to a lab for testing. Then you will have an ultrasound performed by an ultrasound specialist. This lasts for 20-40 minutes. You will get the results in about a week after the testing.

First Trimester ScreeningRisks or side effects of screening in the first trimester

It is true that drawing blood is somewhat uncomfortable, but besides this there aren’t any known risks or side effects for the baby or you. Nonetheless you should know that there is a risk of 5% for a false negative. It is possible that you will have abnormal results, but the further testing will show that there is nothing wrong with the baby.

When is the screening performed?

Just as the name suggests, the first trimester screening is performed in the first trimester, between weeks 11 and 13. Since it is done at an early stage, it shows doctors whether you need to have some early diagnostic tests, such as amniocentesis or chorionic villus sampling.

What does it look for?

Screening in the first trimester is meant to find abnormalities. For example the babies who don’t have any chromosomal abnormalities could have too much fluid in the nuchal translucency. Also the doctors could find high or low PAPP-A or hCG levels. The result of the test is a combination of these three.

In case of the first trimester screening there are some other factors taken into consideration as well, such as age risk factors. In the end you will have the risks for the baby to have any chromosomal abnormalities. Keep in mind that although it is more than estimation, it cannot be 100% accurate.

What do the results mean?

As it has been mentioned, screening in the first trimester is just a screening test, and it doesn’t have the accuracy of a diagnostic test. It just refers to the risks for the baby to have abnormalities. The false positive result has also been mentioned before.

The false positive in case of the first trimester screening means that although you have abnormal results in case of this test, other tests may show that there is nothing wrong with the little one. It is possible that the screening will not offer you specific results in numbers.

The doctors will tell you whether the results of the screening in the first trimester are normal or abnormal. The genetic counselor will also provide you with a risk factor according to the results. In case your results are abnormal, you will need some further tests.

If you have first trimester screening you will be working with a genetic counselor who will explain to you the results and he or she will also help you with the decision regarding other tests that you could have, such as amniocentesis or CVS.

In case you are advised to have such tests after getting the results of the screening in the first trimester, make sure to discuss them with your counselor and also with your partner since these are invasive procedures. You may also need additional counseling.

You should discuss this with your health care provider before having first trimester screening.


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