Pregnant people have access to various screenings that evaluate the likelihood that their baby has a genetic or other condition. Some tests are a normal part of pregnancy, like an ultrasound. Further tests are optional, which means some families choose them and others don’t.
The quad screen, or maternal serum screen, is an optional screening that a pregnant person can take in the second trimester.
What Is the Quad Screen?
The quadruple screen test, or quad screen, is a blood test. It helps determine if the baby is at risk for certain genetic and other conditions.
It’s called the “quad” because it measures levels of four different pregnancy hormones:
- Alpha-fetoprotein (AFP), which the baby produces.
- Human chorionic gonadotropin (hCG), which the placenta produces.
- Unconjugated estriol (uE3), which the placenta and the baby’s liver make.
- Inhibin A, which the placenta releases.
The quad screen test looks for levels of these hormones that are higher than average or lower than average. A normal test result means that you have normal levels of all four.
The best time to get screened is between weeks 15 and 22, with the most accuracy between weeks 16 and 18. Because it’s just a simple blood test, it is very unlikely it could harm you and poses no increased risk of miscarriage.
What Does the Quad Screen Test For?
The quad screen looks specifically for increased risk for these chromosomal conditions:
- Down syndrome (trisomy 21).
- Edwards syndrome (trisomy 18).
It can also detect an elevated risk for other conditions, including:
- Anencephaly (missing a part of the brain or skull).
- Problems with the baby’s intestines or abdomen.
- Spina bifida (a neural tube condition that affects the baby’s spine).
- Tetralogy of Fallot (a congenital heart condition).
- Turner syndrome (a condition that causes short stature in females).
The quad screen also takes other risk factors into account. For example, it looks at your age, weight, ethnic background, and family history. The test uses both your hormone levels and these risk factors to estimate how likely a certain condition is.
What Do Abnormal Results in the Quad Screen Mean?
As its name suggests, the quad screen is a screening test. This means that it can only assess risk, not diagnose a genetic or other condition.
It can’t tell you conclusively that the fetus has a genetic or other developmental problem. Nor can it completely rule out these or any other conditions that affect babies.
The quad screen is a good tool but can produce false-positive and false-negative results.
If your results are abnormal, your doctor will likely suggest further testing. These tests can include amniocentesis or chorionic villus sample (CVS). These tests are more invasive and carry some risk of miscarriage.
For certain conditions, your doctor may also send you for a diagnostic ultrasound.
Not every pregnant person who gets an abnormal quad screen chooses to have further testing. It can be helpful to talk to a genetic counselor to decide what to do based on your results.
Should I Get the Quad Screen?
The quad screen is available to any pregnant person. People with these risk factors are more likely to have a baby with certain genetic or congenital conditions:
- Being 35 years or older.
- Taking insulin to treat diabetes.
- Having a family history of hereditary or congenital conditions.
When deciding if the quad screen is right for you, consider what you might do with the information, both emotionally and practically. Some results mean you may need to make choices about continuing your pregnancy. Other results can simply help prepare you and your delivery team.
Also, consider whether you are willing to get further testing to confirm a condition. The more invasive tests have risks, but they also provide definitive answers.
Knowing your baby has a certain condition can affect where you deliver and what specialists are standing by. Some conditions require immediate procedures after birth. Conditions like spina bifida may even require procedures while the baby is still in-utero.
Knowing your baby has a certain condition doesn’t mean you will love your baby any less. However, it can help prepare you for the birth.