Risks for fetal abnormalities after very and moderately elevated AF-AFPs

Area of Science:

• Prenatal diagnostics
• Biochemistry
• Genetics

Background:

• Maternal serum screening for fetal abnormalities relies on biochemical markers.
• Alpha-fetoprotein (AFP) in amniotic fluid (AF) is a key indicator for neural tube defects (NTDs) and other congenital anomalies.
• Interpreting AFP levels requires consideration of other diagnostic tests like acetylcholinesterase (AChE).

Purpose of the Study:

• To analyze the correlation between elevated amniotic fluid alpha-fetoprotein (AF-AFP) levels and fetal abnormalities.
• To assess the diagnostic value of AF-AFP in conjunction with acetylcholinesterase (AChE) testing.
• To refine risk assessment for fetal abnormalities based on AF-AFP levels and AChE results.

Main Methods:

• Assay of AFP in 48,412 amniotic fluid samples between 1993 and 1995.
• Categorization of elevated AF-AFP levels into mild (2.0-4.9 MOM), moderate (5.0-9.9 MOM), and very elevated (>= 10.0 MOM).
• Correlation of AF-AFP levels and AChE test results with confirmed fetal abnormalities, including NTDs and congenital nephrosis.

Main Results:

• Abnormalities were detected in 25% of mildly elevated, 88% of moderately elevated, and 98% of very elevated AF-AFP cases.
• Neural tube defects (NTDs) were associated with moderate (45%) and very elevated (36%) AF-AFP levels.
• Positive AChE tests showed high abnormality rates (>95%) in moderate and very elevated AF-AFP groups; negative AChE tests still indicated significant risks (18-55%) in these groups, particularly for congenital nephrosis.

Conclusions:

• Elevated AF-AFP levels, especially above 5.0 MOM, are strongly associated with fetal abnormalities.
• The combination of AF-AFP and AChE testing improves diagnostic accuracy for fetal anomalies.
• High-resolution ultrasound and repeat amniocentesis are recommended for cases with elevated AF-AFP and normal initial findings.