Obstetric blood test panel

Procedure Information

What is an Obstetric blood test panel?

An obstetric panel is a group of blood tests used to check the health of a woman before and during early pregnancy. Results of these tests can help find certain problems during pregnancy. They can also help guide any treatment needed for a woman during pregnancy.

There are blood tests done during the first trimester (known as first-trimester screening) and others done during the second trimester (known as second-trimester screening or quad screening.) There are also other tests like Rh factor and infections like syphilis or hepatitis. 

First-trimester screening (between weeks 11 and 14), also called the first trimester combined test, has two steps:

• A blood test to measure levels of two pregnancy-specific substances like Human chorionic gonadotropin (HCG) and Pregnancy-associated plasma protein-A (PAPP-A).
• An ultrasound to measure the size of fluid-filled subcutaneous space that exists at the back of the fetal neck (known as nuchal translucency).

Second-trimester screening (between weeks 15 and 18) measures levels of four substances in pregnant women's blood:

• Alpha-fetoprotein (AFP), a protein made by the baby.
• Inhibin A, a protein made by the placenta.
• Estriol, a hormone made by the baby’s liver and placenta.
• Human chorionic gonadotropin (HCG), a protein made by the placenta.

Why would I get an Obstetric blood test panel?

First-trimester screening is useful in determining the risk of carrying a baby with Down syndrome. It also provides information about the risk of trisomy 18. 

The second-trimester screening evaluates your chance of carrying a baby who has any of the following conditions:

• Down syndrome (trisomy 21)
• Trisomy 18 
• Spina bifida. Spina bifida is a defect that occurs when the spinal cord and spine don't form properly. 
• Abdominal wall defects. In abdominal wall defects, part of the baby’s intestines or other abdominal organs protrudes through an unusual opening that forms on the abdomen.

What happens during an obstetric blood test panel?

During the test, a member of your health care team takes a sample of blood by inserting a needle into a vein in your arm to collect blood. You can return to your regular activities immediately after the test.

If you do an ultrasound as a part of the first-trimester screening, your health care provider will place a transducer over your abdomen. The reflected sound waves will be converted into images on a monitor. Your health care provider will use these images to measure the size of the clear space in the tissue at the back of your baby's neck.

What to expect after an obstetric blood test panel?

Either it was a blood test or an ultrasound, you will experience no pain, and you can immediately return to your regular activities.

Your doctor will combine your age, results of the blood test, and ultrasound to measure the risk of carrying a baby with down syndrome, trisomy 18, spina bifida, or abdominal wall defects. 

Conclusion

In case of positive quad screen test results, your doctor might recommend an additional ultrasound to verify your baby's gestational age and the number of babies you are carrying. Your doctors and a genetics professional will discuss your options, including additional testing like:

• Amniocentesis
• Prenatal cell-free DNA (cfDNA) screening
• Chorionic villus sampling (CVS)

Your doctor will help you understand your test results and what they might mean for your pregnancy.

Citation

Mayo Clinic: Quad screen

Mayo Clinic: First-trimester screening