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

Objective: The goal of the study was to evaluate the significance of delaye d laboratory analysis of maternal serum alpha-fetoprotein, beta-subunit of human chorionic gonadotropin, and unconjugated estriol for prenatal screeni ng. Methods: Biochemical anaIysis of 30 consecutive biochemical screening s pecimens of maternal serum alpha-fetoprotein, beta-subunit of human chorion ic gonadotropin, and unconjugated estriol was performed immediately upon ar rival to the laboratory, 7 days later, and again 14 days after maternal blo od was drawn. Differences among the results of the three sets of biochemica l studies were evaluated by one-way analysis of variance for repeated measu res. Results: No significant differences were found among the results of im mediate assays as compared with those at a 7- or a 14-day delay for all thr ee biochemical markers. Conclusions: Our data suggest that up to a 14-day d elay in the performance of the 2nd-trimester maternal serum biochemical scr eening assays will not alter the results significantly. The results of mate rnal serum screening are, thus, clinically valid even if the laboratory ass ays were performed several days after maternal blood was drawn.