Quad screen - Definition & Explanation for Mothers

Table of Contents

Definition

A Quad Screen is a prenatal test used to evaluate whether a pregnancy has a higher chance of certain birth defects. It measures levels of four specific substances in a pregnant woman’s blood: Alpha-fetoprotein, human chorionic gonadotropin, unconjugated estriol, and Inhibin A. These levels provide information on the risk of conditions like Down syndrome, Trisomy 18, and neural tube defects.

Key Takeaways

The Quad Screen is a prenatal test that measures levels of four substances in a pregnant woman’s blood. These substances include Alpha-fetoprotein (AFP), Estriol, Human Chorionic Gonadotropin (hCG), and Inhibin A.
This test is typically conducted during the second trimester of pregnancy, roughly between weeks 15 and 20. It helps identify a risk of certain birth defects, like Down Syndrome or neural tube defects. However, it does not confirm any diagnosis and further testing is needed if results are abnormal.
While the Quad Screen can provide important information about potential risks, it also comes with a risk of false positives. Hence, one should use it as a screening tool and not as a definitive diagnostic tool. Additional diagnostic tests, like amniocentesis or chorionic villus sampling, may be required to confirm any potential anomalies.

Importance

The term “Quad screen” in motherhood is significant as it refers to a prenatal diagnostic test performed in the second trimester, typically between 15 and 20 weeks of gestation.

This procedure screens for common chromosomal abnormalities such as Down Syndrome, Edward’s Syndrome, and neural tube defects such as spina bifida.

It specifically measures four substances in a pregnant woman’s blood – alpha-fetoprotein, human chorionic gonadotropin, unconjugated estriol, and inhibin A.

While a Quad screen is not absolute in its diagnosis, abnormal results can indicate an increased risk of a fetus having a genetic disorder or birth defect, warranting further, more definitive testing.

So, the Quad screen is critical in prenatal care, helping doctors and prospective parents make informed decisions about further diagnostic procedures and potential interventions.

Explanation

The Quad screen, often administered during pregnancy, serves as a crucial method to evaluate the risk of specific chromosomal conditions such as Down syndrome (trisomy 21), trisomy 18, or neural tube defects like spina bifida. It is typically conducted during the second trimester, specifically between the 15th and 20th week of pregnancy.

It is known as the “quad” screen because it tests four specific substances in the mother’s blood: Alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and Inhibin-A. The Quad screen isn’t used to diagnose diseases or conditions, but to assess risk levels.

It does this by comparing the levels of these four substances in the mother’s blood, indicating whether there’s a higher or lower likelihood of certain disorders. If a Quad screen results indicate a higher risk, additional diagnostic testing such as ultrasound or amniocentesis can be recommended to confirm a diagnosis.

It’s important to note though, the quad screen only provides risk assessment, not a definitive answer about whether a baby has a genetic disorder or neural tube defect.

Examples of Quad screen

Case One: A 30-year-old woman, Mrs. Smith, goes for a routine prenatal check-up in her second trimester. Her doctor suggests her to undergo a Quad screen test to assess the risk of certain chromosomal and neural tube abnormalities in her unborn baby. The test results come back normal, indicating no increased risk for conditions such as Down syndrome or spina bifida.

Case Two: Another example can be of a 35-year-old pregnant woman, Ms. Johnson, who already has a child with a genetic disorder. During her second pregnancy, she opts for the Quad screen for an early detection of any chromosomal disorder in her unborn child. The test results indicate a higher risk for Down syndrome. Her doctor advises further diagnostic procedures to confirm the results.

Case Three: A prospective mother, Mrs. Lopez, who is in her second trimester undergoes a Quad screen as part of her routine prenatal care. The test results show an increased risk for neural tube defects. To get a definitive diagnosis, her doctor suggests an ultrasound or amniocentesis. After the further testing, it confirmed the initial results. This early diagnosis allows her healthcare professionals to plan for a medical intervention as soon as the baby is born.

Quad Screen FAQs

What is a Quad Screen?

A quad screen, also known as quadruple marker test, is a prenatal test that measures levels of four substances in a pregnant woman’s blood. It’s typically performed during the second trimester, between weeks 15 and 20. This test can provide information about the risk of certain birth defects in the baby.

How is a Quad Screen performed?

The quad screening is a simple blood test. It involves taking a blood sample from a vein in the arm, which is then sent to a lab for analysis. The test measures levels of four different substances in your blood: alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), estriol, and inhibin A.

What does a Quad Screen test for?

The quad screen test can help identify the risk of certain birth defects, including Down syndrome and neural tube defects such as spina bifida. However, it’s important to know that a positive result on the quad screen doesn’t guarantee your baby has a birth defect, but rather, suggests further testing may be necessary.

How accurate is a Quad Screen?

The quad screen can detect about 80% of cases of Down syndrome and other chromosomal abnormalities. It is also able to detect about 80-85% of cases of neural tube defects. However, the test also has a false-positive rate of about 5%, so additional diagnostic tests are typically recommended if a quad screen result is positive.

What to do if a Quad Screen results are positive?

If a quad screen result is positive, it doesn’t necessarily mean that the baby has a birth defect. It indicates that there’s an increased risk for certain conditions. Your doctor will likely recommend follow-up tests, such as an ultrasound or amniocentesis, to obtain more definitive information.

Related Motherhood Terms

Amniocentesis
Genetic Counseling
Prenatal Diagnosis
Gestational Age
Birth Defects

Sources for More Information

Sure, here are four reliable sources for information on the term “Quad screen”: