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Neural tube defect screening

Extracted from Survival Guide to Midwifery, 2nd Edition (2012) Diane M. Fraser and Margaret A. Cooper, Oxford; Churchill Livingstone: 2012. Courtesy Elsevier

Alpha fetoprotein (AFP) is present in fetal serum and amniotic fluid by 6 weeks' gestation. When the fetus has an open neural tube defect, AFP can escape in increased amounts, causing levels to be raised in maternal serum. A blood sample from the mother at 15-18 weeks has a detection rate of 98 per cent but this test has largely been superseded by the use of ultrasound to diagnose a range of neural tube defects.

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