What Prenatal Testing Options Are Available?

*Contributed post by Jenna Smith

Throughout your pregnancy, your doctor will closely monitor the growth and development of your child. In order to do this, he or she will conduct routine screenings and may offer diagnostic tests. Prenatal screening is meant to give your doctor an indication as to what might be a concern for your baby’s health. What Prenatal Testing Options Are Available?

Noninvasive Prenatal Genetic Testing

During pregnancy, DNA associated with the fetus circulates throughout the mother’s body. Using a blood sample from the mother, scientists can analyze this DNA to assess the risk that the fetus may have a chromosomal abnormality. This screening method is referred to as noninvasive prenatal genetic testing. Noninvasive prenatal testing can be done as early as week 10 in your pregnancy. Prenatal diagnostic tests, which are offered if a screening shows a risk is present, will give definitive answers.

 

First Trimester Screening Test

A first-trimester screen is the first screening offered to pregnant women. This screening consists of a two-part test. One part involves collecting a sample of blood from the mother in order to look at two substances: the hormone human chorionic gonadotrophin (hCG) and the protein pregnancy-associated plasma protein A (PAPP-A). The level of each substance could indicate a risk of a chromosomal abnormality.

The other part of a first-trimester screening involves ultrasound imaging. During the ultrasound, the doctor measures the amount of fluid located in a certain region behind the baby’s neck, referred to as the nuchal translucency. The amount of this fluid may indicate a high risk of a chromosomal abnormality. The first-trimester screening test is typically performed between gestation weeks 11 and 13.

Chorionic Villus Sampling

If your doctor believes that your developing baby has a high risk of having a chromosomal or genetic disorder due to the results of screening tests, you will be offered the option of diagnostic testing.

One diagnostic testing option is Chorionic villus sampling or CVS. During this procedure, your doctor guides a needle through your abdomen or cervix using an ultrasound image for guidance. A sample of the placenta is collected and analyzed in order to identify any possible chromosomal abnormalities or genetic disorders. If you choose to get CVS, this procedure is usually performed between gestation weeks 10 and 13.

Triple/Quad Screening Test

Further along in your pregnancy, your doctor may want to monitor levels of specific hormones and proteins in your blood. Using a blood sample from the mother, a triple screening measures
the amount of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and estriol. In a quad screening, all the mentioned substances are measured in addition to Inhibin A. If the levels of one or more of these substances are out of range, this may indicate a high risk of a chromosome abnormality. Triple/quad screening is typically done between gestation weeks 15 and 18.

Amniocentesis

Amniocentesis is a diagnostic testing option that analyzes cells found in the amniotic fluid for chromosomal abnormalities, genetic disorders, or neural tube defects. This procedure involves collecting a sample of amniotic fluid by using an ultrasound image to guide a needle through your abdomen into the uterus. If you choose to get an amniocentesis, this procedure is typically done between gestation weeks 16 and 20.

Still, Have Questions About Prenatal Testing?

If you’d like more information regarding prenatal testing during your pregnancy, talk to your doctor or schedule an appointment with a genetic counselor. When you’re informed, you can make the best decisions regarding your pregnancy.