Second-trimester alpha-fetoprotein and beta-human chorionic gonadotrophin prenatal screening using dried blood spots on filter paper for Down's syndrome

Objective To establish a laboratory method to determine alpha-fetoprotein(AFP) and beta-human chorionic gonadotrophin (β-HCG) using dried blood spots on filter paper and to estimate the efficacy for second-trimester Down's syndrome prenatal screening. Methods AFP and β-HCG were detected by antibody sandwich enzyme-linked inununosorbent assay (ELISA). AFP and β-HCG in serum specimen and samples of dried blood spots on filter paper of were detected in 164 women of 14 to 20 gestational weeks in Baoan District of Shenzhen using the ELISA assay kit provided by PuRingTaiKe Co. Results Compared with the 164 serum samples with ELISA assay, all the correlation coefficients (r) were over 0.92, indicating a good correlation. According to two method examination results, their risk coefficients were calculated with the professional software YOUPUSHENG. In two methods, all have 14 with high risk for Down's syndrome, and 145 women with low risk for Down's syndrome, indicating a concordance of 159 out of 161 (98.6 %). No significant was noted in the results after the dried blood spots on filter paper were saved at 4 degrees centigrade for 3 month. The recovery rate of AFP of dried blood spots on filter paper was 100.4 %, and p-HCG was 94.2 %, with an intraassay coefficient of variation of 10 %, and an interassay coefficient of variation of 15 %. Conclusion Second-trimester AFP and β-HCG using dried blood spots on filter paper can used for prenatal screening for Down's syndrome.