Overview: Alpha-Fetoprotein Maternal TestIntroduction: The Alpha-Fetoprotein Maternal Test measures alpha-fetoprotein (AFP) in pregnant women to screen for birth defects like spina bifida or Down syndrome, ensuring early detection for better care. Following 2023 ACOG guidelines, it uses an immunoassay for high sensitivity, aiding in prenatal screening. This test is critical for guiding further diagnostic testing or interventions, improving fetal outcomes in maternal-fetal medicine.
Other Names: AFP Maternal Assay, Maternal Serum AFP Test.
FDA Status: Laboratory-developed test (LDT), meeting immunology standards for prenatal screening.
Historical Milestone: AFP was linked to birth defects in the 1970s. Immunoassays emerged in the 1980s, and by the 2000s, integrated screening protocols improved diagnostic accuracy.
Purpose: Screens for birth defects, guides prenatal care, and monitors pregnancy in women with risk factors or abnormal ultrasound findings.
Test Parameters: 1. Alpha Fetoprotein (Maternal)
Pretest Condition: No fasting required. Collect serum between 15-20 weeks of gestation. Report pregnancy history, ultrasound findings, or family history of birth defects.
Specimen: 2-5 mL serum (SST). Centrifuge within 1 hour. Transport in a biohazard bag within 8 hours.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 7 days
Sample Stability at Frozen: 6 months
Medical History: Document gestational age, prior pregnancies, or family history of birth defects. Include ultrasound findings or risk factors.
Consent: Written consent required, explaining the test's purpose, diagnostic implications, and potential need for further testing.
Procedural Considerations: Uses an immunoassay to measure AFP levels. Results are available in 1-2 days, supporting timely prenatal decisions.
Factors Affecting Result Accuracy: Incorrect gestational age or multiple pregnancies may skew results. Hemolysis or improper storage can degrade samples.
Clinical Significance: Elevated AFP suggests neural tube defects; low AFP may indicate Down syndrome, prompting ultrasound or amniocentesis.
Specialist Consultation: Consult an obstetrician or maternal-fetal medicine specialist for result interpretation. Genetic counseling is advised for abnormal results.
Additional Supporting Tests: Ultrasound, amniocentesis, or quad screen to confirm birth defects.
Test Limitations: Non-specific AFP changes require confirmatory testing. False results may occur with improper timing or multiple gestations.
References: ACOG Prenatal Screening Guidelines, 2023; Wald NJ, New England Journal of Medicine, 2022.
