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What is the quad marker screening test?
The quad marker screening test (quad screen) is a blood test administered in pregnancy, typically between the 15th and 20th weeks of gestation. Similar to the triple screen, the quad marker screen provides information about whether there is an increased risk for certain birth defects in the baby. The test is simple and involves taking a blood sample as for any other routine blood test. The quad marker test is a screening test, meaning that it gives information about risk, but it does not allow the definitive diagnosis of any conditions. It can only signal that further testing should be done to confirm a diagnosis. There is no risk to the baby from the test.
What substances are measured in the quad marker screening test?
The quad screen looks at the three substances also measured in the triple screen (alpha-fetoprotein, human chorionic gonadotropin, and estriol) test plus one additional substance, inhibin A.
- Alpha-fetoprotein (AFP) is produced by the liver of the fetus
- Human chorionic gonadotropin (hCG) is a hormone made by the placenta
- Estriol is an estrogen made both by the placenta and the liver of the fetus
- Inhibin-A is another hormone made by the placenta
Quick GuideEarly Signs & Symptoms of Pregnancy
How accurate is the quad marker screening test?
The test is a screening test only, and is not 100% accurate. It can predict about 85% of open neural tube defects, problems with the development of the baby's brain and spinal cord. It predicts about 80% of fetuses with Down syndrome in women over age 35 and about 75% in younger women. The fact that it is not 100% accurate means that not all women who have a positive high risk result on the quad screen will have a fetus with a birth defect, and the test may also be normal even in the presence of birth defects.
For example, about 50 women out of every 1,000 will have a result on the quad screen that indicates an increased risk of a birth defect, but only one to two of those women will actually have a baby with an open neural tube defect. About 40 women out of 1,000 will have a result indicating an increased risk of Down syndrome, but only one to two of these women will have a baby with Down syndrome.
Who should receive the quad marker screening test?
The test should be offered to all pregnant women who desire to have the test. It is done between the 15th and 20th week of gestation, most commonly between the 16th and 18th weeks. Because of some of the uncertainty surrounding the test, not all women choose to have the test. Most doctors particularly recommend the test for women older than 35 years of age, women with type 1 diabetes, and in women that have a family history of birth defects.
What does an abnormal result of the quad marker screening mean?
As with any screening test, an abnormal result does not mean that the fetus definitely has a birth defect or genetic condition. It only means that the blood levels of these four substances suggest that a woman's risk is increased of having a baby with certain conditions. Women who have a result suggesting increased risk are typically offered further testing. This can include repeating the quad screen and/or having a high definition ultrasound examination to look for signs of birth defects or abnormalities in the developing baby. If this testing is abnormal, the mother may be offered the choice to undergo amniocentesis. Amniocentesis involves withdrawing a sample of amniotic fluid for genetic and chromosome testing, and it can definitively establish the diagnosis of genetic and chromosomal problems in most fetuses. Amniocentesis carries a small risk of miscarriage (fewer than 1% of fetuses tested).
Medically reviewed by Wayne Blocker, MD; Board-Certified Obstetrics and Gynecology
REFERENCE: American Pregnancy Association. Quad screen.
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REFERENCE: American Pregnancy Association. Quad screen.
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Top Quad Marker Screen Test Related Articles
Alpha-fetoprotein Blood TestAlpha-fetoprotein (AFP) blood test is the most widely used biochemical blood tests. High levels of AFP in the blood are seen in three situations; HCC (hepatocellular carcinoma), cancer of the testes or ovaries, and liver cancer.
AmniocentesisDuring an amniocentesis, a sample of the amniotic fluid is taken to screen for certain birth defects (Down's syndrome, neural tube defects, spina bifida, cystic fibrosis), lung maturity of the fetus, infection, or chromosome analysis. Amniocentesis is recommended for women giving birth after the age of 35.
Birth DefectsBirth defects have many causes and currently, are the leading cause of death for infants in the first year of life. Some of the causes of birth defects include genetic or chromosome problems. Exposure of the mother to rubella or German measles during pregnancy, or using drugs or alcohol during pregnancy. The treatment for birth defects depends upon the condition of the effected child.
Down Syndrome OverviewGet the facts on Down syndrome, a genetic disorder caused by an additional set of chromosomes in a developing fetus. Down syndrome signs and symptoms include:
- distinctive facial features,
- growth retardation, and
- decreased mental function and IQ.
Signs and symptoms of pregnancy vary by stage (trimester). The earliest pregnancy symptom is typically a missed period, but others include
breast swelling and tenderness,
- nausea and sometimes vomiting,
- fatigue, and
Second trimester symptoms include
- weight gain,
- itching, and
- possible stretch marks.
Third trimester symptoms are
- additional weight gain,
- swelling of the ankles,
- fingers, and face,
- breast tenderness, and
- trouble sleeping.
Eating a healthy diet, getting a moderate amount of exercise, also are recommended for a healthy pregnancy. Information about the week by week growth of your baby in the womb are provided.
Pregnancy Drug DangersTaking prescription medications or over-the-counter drugs or supplements should be discussed with your doctor. There are some medications that have been found to cause no problems in pregnancy, however, medications such as Accutane for acne, should never be taken during pregnancy.
Pregnancy Induced HypertensionPreeclampsia is related to increased blood pressure and protein in the mother's urine. Preeclampsia typically begins after the 20th week of pregnancy. When preeclampsia causes seizures, it is termed "eclampsia" and is the second leading cause of maternal death of in the US. Preeclampsia is the leading cause of fetal complications. Risk factors for preeclampsia include high blood pressure, obesity, multiple births, and women with preexisting medical conditions such as diabetes, kidney disease, rheumatoid arthritis, lupus, or scleroderma. Pregnancy planning and lifestyle changes may reduce the risk of preeclampsia during pregnancy.
Pregnancy Planning (Preparing for Pregnancy)
Pregnancy planning is an important step in preparation for starting or expanding a family. Planning for a pregnancy includes:
- Taking prenatal vitamins
- Eating healthy for you and your baby
- Disease prevention (for both parents and baby) to prevent birth defects and infections
- Avoiding certain medications that may be harmful to your baby
- How much weight gain is healthy
- Exercise safety and pregnancy
- Travel during pregnancy
Pregnancy Symptoms Am I Pregnant
Pregnancy symptoms can vary from woman to woman, and not all women experience the same symptoms. When women do experience pregnancy symptoms they may include symptoms include
- missed menstrual period,
- mood changes,
- lower back pain,
- breast tenderness, and
Symptoms in late pregnancy include leg swelling and shortness of breath. Options for relief of pregnancy symptoms include exercise, diet, and more.
Pregnancy: Pain Relief Options for BirthWomen experience and tolerate pain differently. For some pregnant women, focused breathing is all they need to get through labor and childbirth; but for others, numbing of the pain is desired. There are a number of different medications a woman can take during labor and childbirth. It is important for you to learn what pain relief options are available. Please discuss the options with your health care provider well before your "birth day" so that when you are in labor you understand the choices.
Pregnancy: Preeclampsia and EclampsiaPreeclampsia is a condition in pregnant women marked by high blood pressure and a high level of protein in the urine. Eclampsia occurs when preeclampsia goes untreated. Eclampsia can cause coma and death of the mother and baby. Preeclampsia symptoms include rapid weight gain, abdominal pain, headaches, blood in the urine, dizziness, and excessive vomiting and nausea. The only real cure for preeclampsia and eclampsia is the birth of the baby.
Pregnancy: Prenatal Care and TestsPrenatal care is important for the health of the mother and the baby. Common prenatal tests include ultrasound, amniocentesis, screening for group B strep, and chronic villus sampling. Prenatal care also helps detect health conditions related to pregnancy, such as preeclampsia and gestational diabetes. Prenatal care costs can be expensive, but services are available to help women get the care they need.
Pregnancy: Your Guide to Eating Right
When a woman is pregnant she needs more vitamins, minerals, and other foods in her diet to stay healthy and deliver a healthy baby. A healthy pregnancy diet menu plan should consist of lots of fruits, vegetables, lean meats (unless you are vegan or vegetarian), and dairy. Examples of healthy pregnancy diet meal plans include:
- Holistic pregnancy diet
- Vegan or vegetarian diet
- Low-carb diets
Begin your healthy eating plan around three months before you begin trying to conceive, and follow the same eating plan until after you have stopped breastfeeding. If you are overweight or obese, being pregnant is not the right time to try to lose weight. Discuss your options with your health-care professional.
Spina Bifida and AnencephalySpina bifida is the most common neural tube defect in the United States. There are four types of spina bifida; 1) occulta, 2) closed neural tube defects, 3) meningocele, and 4) myelomeningocele. The cause of spina bifida is not known. Theories include genetic, nutritional, and environmental factors. Lack of folic acid during pregnancy is highly suspected. Symptoms of spina bifida vary from individual to individual. Treatment depends on the type of spina bifida the person suffers.
Third Trimester Tests During PregnancyTesting is often recommended during the third trimester of pregnancy. These tests are designed to ensure the health and safety of both the child and mother. Common tests during the third trimester of a woman's pregnancy include:
- group B streptococcus screening,
- electronic fetal heart monitoring,
- nonstress test,
- contraction stress test, and
- a biophysical profile.