ALPHA-FETOPROTEIN SCREENING (AFP)

• Measures the quantity of fetal serum proteins.
• An elevated result is associated with open neural tube defects. A significantly decreased amount means chromosomal defects such as Down's Syndrome.
• Assessed with single maternal blood sample drawn at 15-18 weeks gestation.
• If increased in less than 18 weeks of gestation, a second sample is drawn. Level 2 ultrasound is also performed to rule out fetal abnormality, multiple gestation, or fetal death.