2nd-trimester maternal serum marker results are not altered by delayed analysis

Objective: The goal of the study was to evaluate the significance of delayed laboratory analysis of maternal serum α-fetoprotein, β-subunit of human chorionic gonadotropin, and unconjugated estriol for prenatal screening. Methods: Biochemical analysis of 30 consecutive biochemical screening specimens of maternal serum α-fetoprotein, β-subunit of human chorionic gonadotropin, and unconjugated estriol was performed immediately upon arrival to the laboratory, 7 days later, and again 14 days after maternal blood was drawn. Differences among the results of the three sets of biochemical studies were evaluated by one-way analysis of variance for repeated measures. Results: No significant differences were found among the results of immediate assays as compared with those at a 7- or a 14-day delay for all three biochemical markers. Conclusions: Our data suggest that up to a 14-day delay in the performance of the 2nd-trimester maternal serum biochemical screening assays will not alter the results significantly. The results of maternal serum screening are, thus, clinically valid even if the laboratory assays were performed several days after maternal blood was drawn.