Clinical evaluation of a single antibody RIA assay for alpha-fetoprotein

Area of Science:

• Obstetrics and Gynecology
• Medical Diagnostics
• Biochemistry

Background:

• Open neural tube defects (ONTDs) are birth defects associated with elevated alpha-fetoprotein (AFP) levels.
• Maternal serum and amniotic fluid AFP levels are used as screening markers.

Purpose of the Study:

• To evaluate the efficacy of maternal serum and amniotic fluid alpha-fetoprotein (AFP) testing for screening neural tube defects (NTDs).
• To assess the false-negative and false-positive rates of AFP screening for NTDs.
• To address concerns regarding potential increases in amniocentesis due to serum screening.

Main Methods:

• Prospective study involving 1,049 maternal serum and 1,211 amniotic fluid specimens collected between 14-20 weeks of gestation.
• AFP levels determined using radioimmunoassay (RIA).
• Gestational dating confirmed by ultrasound.

Main Results:

• Serum AFP screening identified 25 infants with NTDs out of 1,049 subjects.
• False-negative rate for serum AFP was 0.38%; false-positive rate was 0.29%.
• Amniotic fluid AFP screening identified 23 infants with NTDs; false-negative rate was 0.25% with no false positives.

Conclusions:

• Maternal serum alpha-fetoprotein (AFP) screening is a valuable tool for detecting neural tube defects (NTDs).
• The study demonstrates low false-negative and false-positive rates for serum AFP screening.
• Serum screening does not appear to lead to an increase in unnecessary amniocentesis procedures.