Description
Overview: The “Quad Screen” improves upon the older “Triple Screen” by measuring four specific markers in the mother’s blood:
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Alpha-fetoprotein (AFP): Produced by the baby’s liver.
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Human Chorionic Gonadotropin (hCG): Produced by the placenta.
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Unconjugated Estriol (uE3): Produced by the placenta and the baby’s liver.
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Inhibin A: Produced by the placenta (this fourth marker increases the sensitivity of detecting Down Syndrome).
Clinical Significance:
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Chromosomal Abnormalities: It calculates the statistical risk of Down Syndrome (Trisomy 21) and Edwards Syndrome (Trisomy 18).
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Neural Tube Defects: High levels of AFP may indicate open neural tube defects, such as Spina Bifida (an opening in the spine) or Anencephaly.
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Screening, Not Diagnosis: This is a screening test. A “positive” or “high-risk” result does not mean the baby has a problem; it simply means further diagnostic testing (like amniocentesis or high-resolution ultrasound) is recommended to confirm.
When is this test recommended?
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Optimally performed between weeks 16 and 18 of pregnancy, though it can be done from week 15 to 20.
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It is often recommended for women who missed the “First Trimester Screening” window.
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For women aged 35 or older, or those with a family history of birth defects.
Sample Requirements:
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Specimen: Serum (Blood).
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Container: Gold Top (SST) or Red Top Tube.
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Preparation: No fasting is required, but accurate information about the gestational age (weeks of pregnancy) is critical for valid results.
