The Pregnancy Quadruple Marker Test Made Easy

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I learned about the quadruple marker test, more commonly known as, the pregnancy quad test during my maternal rotation in nursing school.

But I didn’t really understand what it was and what it tested for. Not until I was pregnant with my second baby.

The quadruple marker test or quad test is part of the routine pregnancy blood work. And all of my results came back good (as in not high-risk) for my first pregnancy. That’s why I never looked into the quad screen test.

However, a few weeks after taking the quadruple marker test during my second pregnancy, I received a phone call from my OBGYN that it came back high-risk for Down Syndrome.

And this is when I started really learning what the quad screen test was.

So in this blog post, I wanted to highlight some of the important things about the pregnancy quad test and also intertwine my personal experience.

And some additional information I gathered while restlessly looking at a ton of pregnancy forums for other women’s experiences with the quad screen.

Who Takes The Quadruple Marker Test

The quad marker screening test is offered to all pregnant women between the 16th and 18th week of pregnancy.

The pregnancy quad test is typically a routine blood work test. But some hospitals and clinics will skip the quad screening and have you take a different blood test called the noninvasive prenatal testing or the NIPT.

(Side note for my Tricare prime moms. I learned that the NIPT is a more expensive blood test screen which is why it’s only given if your quad screen comes back high-risk.)

After my quadruple marker test came back high-risk for Down Syndrome, I had to take the NIPT.

What Is The NIPT

The NIPT is a highly accurate screening test for certain genetic conditions (such as Down Syndrome, Patau Syndrome, and Edward Syndrome).

The reason why the NIPT blood test was given to me after my quad screen came back positive was because it is a more expensive test.

It measures the fetal cfDNA in the mother’s bloodstream, which comes from the placenta.

The NIPT is considered more accurate than the quad screen because the quad screen is a maternal blood screening test.

What Is The Quadruple Marker Test?

The quadruple marker tests for alpha-fetoprotein (AFP) a protein made by the baby, human chorionic gonadotropin (HCG) which is the hormone made by your placenta, estriol a hormone made by the placenta and the baby’s liver, and inhibit A which is another hormone made by the placenta.

The quad test isn’t a diagnostic test meaning it doesn’t diagnose anything. It’s just a test that screens and evaluates whether your baby has an increase risk for certain genetic conditions or neural tube defects.

And the most common reasons for an elevated AFP levels are due to inaccurate dating of your pregnancy.

Genetic Conditions And Neural Tube Defects Screened

The quadruple marker tests for Down Syndrome (trisomy 21), Edwards Syndrome (trisomy 18), spina bifida, and other types of chromosome abnormalities.

Factors That Can Affect The Quadruple Marker Test

There are certain things that are taken into account when doing the quad screen that I didn’t know about until my OBGYN was explaining the results to me.

And these factors can alter your result giving you a false high-risk or even low-risk. That’s why it’s important to know that the quad screen is just a screening test and NOT a diagnostic test.

Factors that can affect your quad test results include

  • A miscalculation of how long you’ve been pregnant
  • Your race
  • Weight
  • Carrying more than one baby
  • Diabetes
  • IVF
  • Smoking during pregnancy

My original due date from my last menstrual period was changed at my first ultrasound that could have caused a high-risk indication on the quad screen test.

The quad screen results give the level of risk of carrying a baby who has certain conditions compared with the general population’s risk. 

And this is where they might give you a number that looks like a ratio. For example, my risk ratio was 1:250 for Down Syndrome. This meant that about one in 250 women who took the quad test, received a positive result.

A typical false positive rate cut-off for Down Syndrome is 1:270 (numbers ranging). And the lower your ratio, the greater the risk. 

When Is The Quad Screen Test Given?

The quad screen test is given sometime in your second trimester, typically between 15 to 18 weeks of pregnancy. But it can also be given up to 22 weeks.

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After The Quadruple Marker Test

If you get a high-risk indicator on your quadruple marker test, there are additional testing your OBGYN will most likely order.

I was ordered the NIPT, another blood test. But there are other tests like the prenatal cell-free DNA screening, targeted ultrasound, chorionic villus sampling, and an amniocentesis.

Final Thoughts

You might be freaking out like I did when I got a call from the OBGYN that my pregnancy quad test came back high-risk for Down Syndrome (or a different chromosomal abnormality).

But try your best to breathe and not stress. Talk to your OBGYN about the next steps and additional testing.

Because remember, the quadruple marker test is not a diagnostic test. This means it isn’t a test that tells you that your baby will 100% have whatever you showed high-risk for.

It is simply a screen test and one that is a lot more inaccurate than you think. A lot of women have experienced false high-risk results.

However, if you do take additional tests and the results are still high-risk, there are a lot of resources out there.

I hope this post helped clarify some things and benefited you in any way possible! Feel free to comment below for any other questions!

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