The quadruple marker test, also called the quad screen, is a prenatal test used to assess the risk of birth defects in a baby. It screens for conditions like Down syndrome, neural tube defects, trisomy 18 (Edward’s syndrome), and abdominal wall defects. The test involves drawing a blood sample from the mother for analysis, a simple procedure performed by a trained technician called a phlebotomist. No special preparation is needed, and the mother can eat and drink normally before the test. The quad screen is typically performed during the second trimester.
• Purpose
• Procedure
• Risks
• Preparation
• Results
• Cost
This test evaluates the pregnancy for the likelihood of specific conditions such as Down syndrome, neural tube defects, trisomy 18, and abdominal wall defects. If the results suggest the presence of any of these conditions, further screening and testing may be recommended.
The levels of biomarkers tested change as pregnancy progresses, so knowing the pregnancy stage is important before taking the test. Each biomarker is associated with certain fetal abnormalities. For instance, high levels of alpha-fetoprotein (AFP) can indicate neural problems like spina bifida, while low AFP levels may suggest Down syndrome.
Based on the pregnancy timing and symptoms, additional prenatal tests such as an ultrasound or other blood tests may be recommended alongside the quad screen.
The test is performed by a phlebotomist, a technician specialized in drawing blood. Here’s how the process works:
• Pretest: The mother checks in and provides necessary documents such as identification and payment information. Consent forms may also need to be signed to ensure medical confidentiality.
• During the Test: The phlebotomist confirms the mother's identity and asks her to sit comfortably. A tourniquet is applied to the non-dominant arm, and the area is cleaned before inserting the needle to collect blood. The process takes about 20 seconds.
• Post-test: After the blood sample is collected, pressure is applied to stop any bleeding. If bleeding continues, the mother is advised to apply pressure or consult a doctor.
There are generally no physical risks associated with the quadruple test. However, it can cause anxiety for families, and in some cases, test results lead to difficult decisions or emotional stress. There may also be slight bleeding after the blood is drawn, which should be monitored.
No specific physical preparation is required, but emotional preparation is important due to the potential outcomes of the test. Consider the following:
• Timing: Consult with your doctor to determine the best time to take the test.
• Location: Clinics recommended by doctors are the usual places for this test.
• Clothing: Wearing half sleeves can make the blood draw easier. You may want to bring an extra layer if you feel cold after the blood draw.
• Food and Drink: There are no restrictions on eating or drinking before the test.
• What to Bring: It’s advised to eat something beforehand to prevent dizziness, and bringing water or a protein snack is a good idea.
Test results are typically available in about a week. The results include numerical values for the four hormones tested. Your doctor will interpret the results, and you may be able to access them online through your medical records.
• AFP: High AFP levels suggest neural issues like spina bifida; low levels may indicate Down syndrome.
• Estriol: Low estriol levels are associated with Down syndrome, anencephaly, or Edwards syndrome.
• HCG: High levels of HCG may indicate Down syndrome; low levels can suggest anencephaly or Edwards syndrome.
• Inhibin A: Elevated levels of inhibin A are associated with Down syndrome.
High HCG levels may also indicate multiple pregnancies. The quad screen results must be evaluated carefully, as they may overestimate or underestimate risks. Further tests may be needed for a more accurate diagnosis.
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