Analysis of maternal α‐fetoprotein: A comparison of three radioimmunoassays

摘要

AbstractIncreased levels of α‐fetoprotein in maternal serum or amniotic fluid may be indicative of a fetal neural tube defect. The present investigation compares, prospectively and retrospectively, the analysis of serum or amniotic fluid α‐fetoprotein from humans using three radioimmunoassays. A total of 46 sera and 137 prospective and 202 retrospective amniotic fluid samples collected at 12–26 weeks' gestation were assayed using our in‐house Farr technique assay, a kit Farr technique assay, and a kit double‐antibody assay. Analysis of quality control data in all three assays showed that within‐ and between‐assay variations were less with the double‐antibody technique. Additionally, the double‐antibody assay offers the advantage of considerably lower nonspecific binding (1.7% vs 16–18% for the Farr technique assays). Of the 375 pregnancies sampled during this study, 340 (91 %) resulted in normal singleton births, whereas three (1 %) pregnancies were found to have elevated serum or amniotic fluid by all three assay methods and resulted in confirmed neural tube defects. Of the remaining, non‐normal outcome without neural tube defect or elevated α‐fetoprotein was determined in 27 (7%) pregnancies, and false‐positive elevated α‐fetoprotein levels were found for 5 (1 %). Analysis of maternal α‐fetoprotein by radioimmunoassay is a sensitive and accurate adjunct in the prenata