Aim: The uncertainty of measurement is an important indicator for both the expediency of a method and the reliability of analytical results obtained in a laboratory. Accreditation processes such as ISO 15189 also expect laboratories to have a defined method for measurement uncertainty and to provide measurement uncertainty results when requested. In this study, our aim is to calculate the measurement uncertainty of the biochemistry parameters used in the first and second trimester prenatal screening tests and compare these values with the total allowable error rates.

Material and Methods: Measurement uncertainty for pregnancy-associated plasma protein-A (PAPP-A), free beta human chorionic gonadotropin (fß-hCG), alpha feto protein (AFP), human chorionic gonadotropin (HCG) and unconjugated estriol (uE3) parameters used in prenatal screening tests in our laboratory were calculated as defined by the European accreditation guide in the Nordest guide and the Eurolab technical report ISO 21748 guide. Internal quality control and external quality control results were used in these calculations.

Results: The measurement uncertainty values were 16.4% for AFP, 17.04% for fβ-hCG, 27.84% for HCG, 18.54% for PAPP-A and 22.52% for uE3. In our study, the highest measurement uncertainty was found for HCG and uE3 parameters, while the lowest measurement uncertainty was found for AFP.

Conclusion: In our laboratory, measurement uncertainties of biochemical parameters of prenatal screening tests were calculated. The measurement uncertainty of HCG, PAPP-A and uE3 tests was found to be high. It is important to interpret the results by considering the measurement uncertainty, especially in prenatal screening tests close to the cut-off value in terms of risk.