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Definition
By Mayo Clinic staffThe quad screen — also known as the quadruple marker test or simply the quad test — is a prenatal test that measures levels of four substances in a pregnant woman's blood:
- Alpha-fetoprotein (AFP), a protein made by the developing baby
- Human chorionic gonadotropin (HCG), a hormone made by the placenta
- Estriol, a hormone made by the placenta and the baby's liver
- Inhibin A, another hormone made by the placenta
Typically, the quad screen is done between weeks 15 and 20 of pregnancy — the second trimester.
Results of the quad screen indicate your risk of carrying a baby who has certain chromosomal conditions, such as Down syndrome. The alpha-fetoprotein part of the test can help detect neural tube defects, such as spina bifida.
If your risk level is low, the quad screen can offer reassurance of a healthy pregnancy.
If your risk level is moderate or high, you might choose to follow the quad screen with another test that's more definitive.
- Canick JA, et al. Second trimester maternal serum screening for Down syndrome. http://www.uptodate.com/index. Accessed Aug. 27, 2012.
- Canick JA, et al. Laboratory issues related to maternal serum screening for Down syndrome. http://www.uptodate.com/index. Accessed Aug. 27, 2012.
- Canick JA, et al. First trimester and integrated screening for Down syndrome and trisomy 18. http://www.uptodate.com/index. Accessed Aug. 27, 2012.
- NINDS anencephaly information page. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/anencephaly/anencephaly.htm. Accessed Aug. 27, 2012.
- NINDS spina bifida information page. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/spina_bifida/spina_bifida.htm. Accessed Aug. 27, 2012.
- Ostermaier KK. Management of Down syndrome. http://www.uptodate.com/index. Accessed Aug. 27, 2012.
- Routine tests in pregnancy. American College of Obstetricians and Gynecologists. http://www.acog.org/~/media/For%20Patients/faq133.pdf?dmc=1&ts=20120827T1517335564. Accessed Aug. 27, 2012.
- Bianchi DW, et al. Genome-wide fetal aneuploidy detection by maternal plasma DNA sequencing. Obstetrics & Gynecology. 2012;119:890.
- Harms RW (expert opinion). Mayo Clinic, Rochester, Minn. Aug. 28, 2012.
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