Title:Deciding by numbers: the genesis of prenatal serum screening cut-off limits for Down syndrome and neural tube defects

Author:M Legge, R Fitzgerald.

Abstract:The use of maternal blood markers and early ultrasound measurements to screen for fetal neural tube defects and fetal aneuploidy (primarily trisomy 21, Down syndrome) is now a well-established practice in many countries. However, the origins and background relating to how the techniques became established and how the various action limits were derived is not universally known or understood. In this paper, we consider the historical origins of the maternal blood screening tests, the establishment of the analytical parameters currently in use, the development of the nuchal translucency test and the integration of multiple analytical parameters to facilitate the diagnosis of fetal abnormalities.
Key words: prenatal diagnosis, Down syndrome, neural tube defects, chromosome aneuploidy, cut-off limits.
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