Effects of hematocrit on prenatal Down syndrome screening results by dried blood method
Zhou Yu-xia · Shandong yiyao · 2010
Objective To explore the effects of hematocrit(HCT) on prenatal Down syndrome screening results by dried blood method.Methods A series of whole blood samples derived from the original blood were created by altering the ratio of plasma and red blood cells.The amout of AFP and β-hCG in the whole blood samples with different HCT were tested;The ratio of AFP(β-hCG) concentration in whole blood and plasma was calculated,and were compared with the ratio of the volume of plasma and the volume of whole blood,then the AFP(β-hCG) distribution in plasma and RBC was analyzed;by making the whole blood calibrator and dried blood spots which had different HCT,the impact of different HCT on AFP(β-hCG) concentration in the whole blood and dried blood spots was analyzed;1 155 pregnancies were divided into three groups according to the magnitude of HCT,and AFP/β-hCG concentration in dried blood spots between three groups were compared;1 320 pregnancies were screened Down syndrome with the dried blood samples and the serum samples,the two method screening results were compared.Results In the same samples with different HCT,no significant difference were found between the whole blood to plasma ratio of AFP/β-hCG concentration and the ratio of the volume of plasma and whole blood,there were no AFP/β-hCG in the RBC;AFP/β-hCG concentration in dried blood spots maintained constant when HCT changed,but changed in whole blood with the change of HCT.The coincidence of Down syndrome screening results between dried blood samples and serum samples were 98.6% according to 1 320 pregnancies results.Conclusion HCT has no significant influence on Down syndrome screening results using dried blood sample,so dried blood sample can substitute serum sample.