Boston: Early Pregnancy: Screening Tests Encouraged But Not Compulsory

Boston,

During her pregnancy a woman is offered various tests to identify possible chromosomal abnormalities in her unborn baby. These tests are not compulsory and the decision whether or not to have them performed is entirely down to the expectant mother and her partner. However, women will be encouraged to have the tests if they fall into one or more of the following categories:

1. They are over 35 years of age.

2. They have had a previous pregnancy where the foetus was affected by an abnormality.

3. They have taken drugs known to pose a risk to the unborn child.

4. There is a history in either the mother or father’s family of genetic abnormality.

The tests are divided into two categories; the first are known as screening tests and are non-invasive procedures use to identify those women who have and increased risk of having a baby with an abnormality and then to quantify that risk. The second set of tests are known as diagnostic tests and are used to give a definitive answer to whether or not the baby has an abnormality. These tests are invasive and as they carry a small risk of inducing miscarriage are only performed if previous screening tests have identified a risk of abnormality.

The screening tests are performed during the first trimester and possibly early in the second trimester. They are looking to identify increased risk of Down’s syndrome and other chromosomal abnormalities and also neural tube defects such as spina bifida and hydrocephalus. Nuchal Translucency screening is a specific ultrasound scan which measures the thickness of the fluid layer at the back of the baby’s neck.

The accuracy of results obtained by this test are further increased when combined with maternal blood test and correlated with the woman’s age. The Triple test is a further maternal blood test carried out at 16 weeks and measures the levels of oestriol, hCG and AFP (alpha feto-protein).

If risk of abnormality has been identified by the screening tests further diagnostic tests will be offered. Chorionic Villi biopsy is performed by taking a sample of tissue from the edge of the placenta (which is genetically identical to the foetus) to detect cystic fibrosis and Down’s syndrome. A sample of the amniotic fluid (containing material shed by the foetus) can also be used for detection of abnormalities (amniocentesis) or alternatively a sample of foetal blood from the umbilical cord (cordocentesis).

Should the tests return a positive result the mother and father will need to think long and hard to come to a decision whether to have the early pregnancy terminated. This is a very controversial subject with pros and cons voiced by various campaigners. However, with guidance and support from the consultant the parents have the right to chose which course of action they wish to take at this difficult time.

As these tests are carried out in early pregnancy the physical health of the mother is less at risk; the psychological effects of a positive test result may take many weeks, months and even years to come to terms with.

Source by Charlotte J Wilson

Early Pregnancy: Screening Tests Encouraged But Not Compulsory