Objective: The aim of this study is to determine the new median values of biochemical analytes used in double and triple prenatal screening tests and to compare these values with the median values of the package program used in screening tests.

Materials and Methods: This study was carried out by obtaining retrospective results of beta-human chorionic gonadotrophin (β-hCG) and pregnant associated plasma protein-A (PAPP-A), alpha-fetoprotein (AFP) and unconjugated estriol (uE3) in which the double and triple prenatal screening tests were performed between October 2013 and October 2015 in the Biochemistry laboratory of Dursun Odabaşı Medical Center of Van Yüzüncü Yıl University.

Results: New median values were calculated from the data between 11-14 weeks free β-hCG and the PAPP-A in the double screening test and compared with the data in Prisca package program. The new median values of β-hCG were significantly lower than the median values of the program (p<0.05), but no difference was found for the PAPP-A. The same procedures were performed in triple screening test's analytes and it was found that the newly calculated median data for alpha fetoprotein, total beta-human chorionic gonadotropin and unconjugated estriol were statistically different from the median data in the program (p<0.05).

Conclusion: In order to reduce the number of invasive procedures used to diagnose conditions such as chromosomal anomalies and neural tube defects, the accuracy and performance of screening tests need to be improved. We believe that each region and even every laboratory must calculate its own median values for prenatal screening tests.