Which prenatal screening marker is commonly elevated in neural tube defects?

Which prenatal screening marker is commonly elevated in neural tube defects?

• A. Beta-hCG
• B. Estriol
• C. Maternal serum alpha-fetoprotein (MSAFP)
• D. Inhibin A

Answer: (C)

Open neural tube defects allow fetal alpha-fetoprotein (AFP) to leak into the amniotic fluid and maternal blood, so maternal serum alpha-fetoprotein (MSAFP) becomes elevated. AFP is produced by the fetal liver and yolk sac, and when the neural tube doesn’t close properly, more AFP reaches the maternal circulation. This is why MSAFP is the screening marker most commonly elevated in these conditions, typically assessed in the second trimester (about 15–20 weeks) as part of routine screening. If MSAFP is high, ultrasound and possibly amniotic fluid testing for AFP and acetylcholinesterase are used to further evaluate. The other markers—beta-hCG, estriol, and inhibin A—are more closely associated with chromosomal abnormalities and are not as indicative of open neural tube defects.

Open neural tube defects allow fetal alpha-fetoprotein (AFP) to leak into the amniotic fluid and maternal blood, so maternal serum alpha-fetoprotein (MSAFP) becomes elevated. AFP is produced by the fetal liver and yolk sac, and when the neural tube doesn’t close properly, more AFP reaches the maternal circulation. This is why MSAFP is the screening marker most commonly elevated in these conditions, typically assessed in the second trimester (about 15–20 weeks) as part of routine screening. If MSAFP is high, ultrasound and possibly amniotic fluid testing for AFP and acetylcholinesterase are used to further evaluate. The other markers—beta-hCG, estriol, and inhibin A—are more closely associated with chromosomal abnormalities and are not as indicative of open neural tube defects.