Routine Tests During Pregnancy
10 Common Tests During Pregnancy – Pregnancy diagnostic tests, also known as prenatal tests, are different from routine pregnancy tests. Pregnancy tests are done to determine whether you are pregnant, while the purpose of a pregnancy diagnostic test is to evaluate your and your baby’s health. These tests are exceptionally vital for you if:
- You are a carrier of specific genetic disorders like thalassemia.
- Your baby is at a higher risk of disease from chromosomal abnormalities like Down’s syndrome.
Therefore, pregnancy diagnostic tests are essential for diagnosing your fetus for any genetic disorder or other problems. These tests enable you to optimize your struggle for your child’s better health. Knowing your child’s condition will help you manage any health-related issues beforehand.
Various tests can be done during different phases of your pregnancy.
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Types of Pregnancy Diagnostic Tests
Pregnancy diagnostic tests are of various kinds. Two major types of prenatal tests are:
- Screening Tests
- Diagnostic Tests
Screening Tests
Screening tests are used to determine the possibility of any genetic or congenital disability in the baby. Your physician may recommend a prenatal screening test depending upon your age and condition, usually during the first and second trimesters.
Congenital disabilities are related to structural abnormalities in a specific part or organ of the baby. These disabilities are not strictly related to genetics; only about 20% of congenital disabilities are due to the genome.
Genetic disorders result from a mutation in genes or chromosomal abnormalities. Genetic diseases are associated with the genome only.
There are the following types of prenatal screening tests:
Early Ultrasound
The early ultrasound test is used to make the image of the baby in your uterus. It manipulates sound waves for this purpose.
This test tells you about the exact time of your pregnancy, the position and size of the fetus, and any possible deformity in the organs and bones.
An example of ultrasound testing is nuchal translucency ultrasound, which checks the total volume of fluid in your baby’s nape (back of the neck). The presence of excessive fluid indicates the risk of Down’s syndrome.
However, the results are not decisive, and your doctor may recommend diagnostic testing.
An ultrasound test is conducted during the early weeks of the first trimester.
Cell-Free Fetal DNA Testing
Cell-free fetal DNA testing or noninvasive prenatal screening determines the possibility of trisomy in your baby. Trisomy is a genetic condition in which some or all of the baby’s cells have an extra chromosome, trisomy results in congenital defects like Patau syndrome and Down’s syndrome.
During pregnancy, your blood contains a small amount of the baby’s DNA extracted using your blood sample. The DNA sample is then checked for a likelihood of trisomy.
Cell-free fetal DNA testing is typically available during the 10th week of your pregnancy.
Early Blood Tests
Early blood sample tests are used to examine your blood for the level of:
- Hormone called human chorionic gonadotropin.
- Pregnancy-associated plasma protein-A.
Suppose there is an abnormal level of both or any of these substances. In that case, your baby might be at risk of chromosomal abnormality.
Early blood tests are done after the 10th week of your pregnancy.
Quad Marker Screening Test
Quad marker screening test, or quad screen, is another prenatal test to assess the probability of genetic disorders in your baby. Word “quad” refers to four substances in your blood.
- Alpha-fetoprotein (AFP):Its lower levels indicate the possibility of Down’s syndrome, while higher levels mean neural tube defect in the baby.
- Estriol: If present in a low amount, it shows that your baby is at a higher risk of Down’s syndrome.
- Inhibin A: High protein levels may cause Down’s syndrome in your baby.
- Human chorionic gonadotropin (HCG): Excessive amount of this hormone means a higher risk of Down’s syndrome in your baby. A quad marker screening test is done during the 15th and 20th weeks of the pregnancy.
Glucose Screening
Glucose screening is a screening test for glucose levels in pregnant women. This test is done to check if you have developed gestational diabetes. High blood glucose levels describe gestational diabetes (GD) only during pregnancy.
Although this type of diabetes does not remain longer and goes away after pregnancy, it can lead to cesarean delivery or C-section. Therefore, checking your blood sugar level is necessary to manage your condition.
Typically, a glucose screening test is performed 24-28 weeks of your pregnancy.
Diagnostic Tests
Screening tests are not decisive. However, your doctor may recommend a diagnostic test if any test shows the danger of genetic or congenital disabilities.
A screening test assesses the possibility of a genetic or congenital disability. In contrast, the diagnostic test is used to confirm the condition.
Therefore, if your screening test shows a positive result for any genetic or birth disorder, your doctor will recommend a diagnostic test to confirm the results.
There are different diagnostic tests, some of which are mentioned here.
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Chorionic Villus Biopsy
Chorionic villus biopsy or chorionic villus sampling is done if:
- You are above 35.
- Your family has a history of any specific genetic disorder.
- Your first screening test shows the risk of genetic abnormality in the baby.
Chorionic villus biopsy is usually performed during the 9th and 12th weeks of the pregnancy.
Chorionic villus sampling is of two types:
- A transcervical test uses a sample from the cervix.
- The transabdominal test takes samples from the abdomen.
This test is invasive and requires a tissue sample from the placenta.
Amniocentesis
Amniocentesis is another prenatal diagnostic test to verify the risk of certain genetic defects in your unborn child. Also known as amino, this test is usually performed during the second or third trimester to validate genetic problems like Down’s syndrome or cystic fibrosis.
During amniocentesis, a sample from the amniotic fluid is taken using a needle. The piece is then tested to corroborate the risk of genetic abnormality. This test checks the levels of a protein alpha-fetoprotein (AFP) and acetylcholinesterase (AChE) in amniotic fluid.
Amniocentesis is generally used to confirm the possibility of diseases like Tay-Sachs, anencephaly, Down’s syndrome, and Rh.
This test is best done during the 15th and 20th weeks of the pregnancy because if performed during the early stage, it may result in miscarriage.
Fetal MRI
Fetal MRI is different from ultrasound. Ultrasound uses sound waves to get an image of the body’s internal organs. On the other hand, in fetal MRI magnetic field is used to create a 3D image of internal structures.
Image produced through MRI is better than that taken through ultrasound; in a sense, it is more detailed. Therefore, fetal MRI is used to validate the result of early ultrasound.
Fetal MRI is used to evaluate the brain and anatomy of your baby for any genetic problem.
Fetal Echocardiogram
A fetal echocardiogram is like an ultrasound. However, it is used to examine the baby’s heart only. This test is usually performed between 18 and 24 weeks of pregnancy.
An echocardiogram uses sound waves that echo off the baby’s heart. And a machine produces an image, an echocardiogram, of these sound waves. The examiner then analyzes this image to assess any possible heart defects in the fetus.
However, a fetal echocardiogram is not recommended for all pregnant women. Your physician will tell you to get the test only if:
- Heart diseases run in your family.
- You already have a baby with congenital heart defects.
- You are an alcohol or drug addict.
- You are suffering from certain diseases like phenylketonuria.
Two main types of echocardiogram are transvaginal echocardiography and abdominal echocardiography.
Preimplantation Genetic Testing
Preimplantation genetic testing (PGT) is performed when you have a baby through in vitro fertilization. Your physician may recommend preimplantation genetic testing if there is a high risk of any congenital disability in your baby.
This test is done before implanting the embryo in your uterus, therefore called the preimplantation test. The primary purpose of this test is to determine any genetic issue in the embryo that may result in no pregnancy at all. Hence, your doctor can use this test to select an embryo with standard genetics, thus lessening the risk of miscarriage.
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Final Words
All the tests mentioned above are not routine, and some depend on your preference or your doctor’s advice. Therefore, it would be best if you consult your doctor before deciding about a custom test if you have a family history of specific genetic disorders.
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