Quad Screen

What is a quad screen?

During your pregnancy, you’ll see your pregnancy care provider every few weeks. Some visits include blood tests and other screenings to keep a close eye on the fetus’s health. The quad screen, or quad marker screen, is one test you may have during your second trimester.

The quad screen is a simple blood test that your provider may do between the 15th and 20th weeks of pregnancy. It can help your healthcare provider determine if the fetus may be at risk for Down syndrome and other genetic disorders.

Why is it called a quad screen?

“Quad” means four. A quad screen measures the levels of four substances in your blood. The four substances are:

• AFP (alpha-fetoprotein).
• HCG (human chorionic gonadotropin).
• Estriol (a form of estrogen).
• Inhibin-A.

What does the quad screen test for?

The quad screen looks at four substances in your blood. Abnormal levels of these substances (either too much or not enough) tell your provider that the fetus may be at risk for having a genetic disorder. Some of those disorders include:

• Trisomy 21 (Down syndrome).
• Trisomy 18 (Edwards syndrome).
• Neural tube defects (NTDs).

It’s important to know that the quad screen is a screening only. Screening tests compare several factors (including age, ethnicity and blood test results), and then estimate the chance that the fetus has a complication. Results of a quad screening may mean that further testing is necessary.

When do I need to have the quad screen done?

Your healthcare provider will ask you if you want the quad marker screen during your second trimester. If you decide to have the screening, it’ll be between the 15th and 20th weeks of your pregnancy. You’ll get the most accurate results between the 16th and 18th weeks.

Does everyone get a quad screen?

No. You don’t have to have a quad screening (it’s optional). But pregnancy care providers recommend that all pregnant women have a quad screen.

How is the quad marker screen done?

The quad screen involves giving a sample of your blood. A phlebotomist will draw blood from a vein in your arm and send it to a laboratory for testing. The test takes about five to 10 minutes.

Is the quad screen safe?

Yes, a quad screen is extremely safe and only involves providing a blood sample. There aren’t any health risks to you or the fetus from a quad screen.

What does the quad screen check?

A quad screen checks for four substances in your blood. The amount of these substances alerts your provider to possible congenital disorders.

• Alpha-fetoprotein (AFP):The fetus’s liver produces AFP. High levels could mean the fetus has a neural tube defect (like spina bifida or anencephaly) or an abdominal wall anomaly (like omphalocele and gastroschisis). But it could also mean that your pregnancy is farther along than you thought or that you’re expecting multiples. Low AFP levels could mean there’s a higher risk of the fetus having Down syndrome.
• Unconjugated estriol (UE):The fetus and placenta (the structure providing oxygen and nutrients to the fetus) produce this hormone. Low levels indicate a higher risk of the fetus being born with Down syndrome.
• Human chorionic gonadotropin (hCG):The placenta makes a hormone called hCG. Levels that are higher than average could mean an increased risk of the fetus having Down syndrome.
• Inhibin-A: Your ovaries and the placenta produce this protein. The risk of having a baby born with Down syndrome increases when inhibin-A levels are higher than expected.

It’s important to understand that the quad marker screening doesn’t mean the fetus has a genetic disorder. It means the risk is higher. Irregular results just mean your provider may recommend further tests to make a diagnosis.

What is a normal quad screen result?

A normal quad marker test result (or a negative result) means the fetus isn’t at higher risk for a congenital disorder. Your provider most likely won’t suggest additional genetic testing. A normal result doesn’t mean for certain that the fetus doesn’t have any complications, it just means the risk is low.

What does an abnormal result of a quad screen mean?

The quad screen only checks your risk. It doesn’t tell you if the fetus has a genetic disorder. So, a positive (or abnormal) result means you may need further testing.

If your quad screen shows an increased risk for a congenital disorder, your healthcare provider will suggest other tests. These tests help determine if the fetus has a genetic disorder. Your healthcare provider may recommend an additional ultrasound or amniocentesis. Be sure to ask your provider any questions you have so you understand the results of your test and the risks and benefits of further testing.

How long does it take to get the results of a quad screen blood test?

You should have results from a quad screen within four to five days. The exact time varies depending on the lab and your provider.

Do I need to have a quad marker screen?

While healthcare providers recommend all pregnant women have a quad marker screen, they can’t make you have the test. It’s best to talk to your provider about the quad screen and its benefits.

What is the difference between NIPT and quad screen?

NIPT (or noninvasive prenatal testing) uses a pregnant woman’s blood to detect congenital abnormalities in the fetus’s DNA. NIPT analyzes fetal DNA present in your blood to screen for abnormalities in the fetus’s DNA. You can have this screening around the 10th week of pregnancy.

The quad screen also uses your blood and screens for congenital abnormalities. The difference is that it looks for the amount of certain hormones and proteins in your blood. The quad screen happens in the second trimester. It screens for slightly different abnormalities than the NIPT.

Both screening tests are screenings — they measure risk only. They don’t diagnose conditions.