Alpha fetoprotein screening and diagnosis of fetal open neural tube defects: the need for quality control

A workshop, held in May, 1978, at the National Institute of Child Health and Human Development, considered the quality control of reagents and assays for measuring alpha fetoprotein (AFP) in maternal serum and amniotic fluid for the antenatal screening and diagnosis of open neural tube defects. The recommendations, published in detail elsewhere and summarized in this article, were based on what was known to be readily achievable and on estimates of the effect of assay performance on screening and diagnostic sensitivity and specificity. Main points considered included: (1) choice of units for AFP measurement and interpretation, (2) need for National AFP Reference Preparations and the need for a scientific panel to assess the adequacy of these reference materials, (3) information needed from reagent manufacturers, (4) criteria for assay performance, (5) biological sources of reagents, (6) need for laboratory and epidemiologic monitoring, and (7) need for a minimum assay workload.