How does ultrasound help after an elevated maternal alpha-fetoprotein result?

When maternal alpha-fetoprotein (AFP) levels are found to be elevated, ultrasound serves as a critical diagnostic tool to investigate the cause. Because high AFP levels can be associated with factors other than neural tube defects, ultrasound is used to rule out alternative explanations, such as multiple pregnancies, fetal death, or an underestimation of the gestational age.12

If these factors are excluded, ultrasound is then employed to perform a more specific assessment for structural fetal malformations, such as spina bifida or anencephaly. In many clinical pathways, ultrasound is also used to provide guidance for more invasive diagnostic procedures, such as amniocentesis, which allows for the direct analysis of amniotic fluid to confirm the presence of AFP and assess chromosomal health.123