Prenatal screening for neural tube defects, quality specification of maternal serum alphafetoprotein analysis.

The bimodal approach for quality specification in prenatal screening for neural tube defects has been used. The method for assessing specifications has been the expenses for the society. It has been shown that the cut-off values and analytical bias are of importance. It is recommended to use a reference serum for local calibration to keep the level within defined limits when changing to a new batch of reagents.