Feasibility of the dried blood specimen method to screen prenatal Down's syndrome among mid-term pregnant women.

Objective To explore the feasibility of the dried blood specimen methods to screen Down's syndrome among mid-term pregnant women.Methods The levels of serum Alpha-fetoprotein(AFP)and free beta-human chorionic gomadotropi(β-hCG)in dried blood specimens on filter paper were detected with the method of time-resolved fluoroimmunoassay.The variation coefficient,recovery rate and detection limit were estimated.Results When the method was used to test AFP,the variation coefficient,recovery rate and detection limit were 2.5%-64.8%,95.1% and 0.5 u/mL respectively.When the method was used to test β-hCG,the corresponding results were 4.1%-7.0%,97.6% and 1 U/mL respectively.The onset risk rate was 1/128,with an accordance rate of 98.4% compared with that of the gold standard of serum screening method which is universally accepted.A total of 1 320 pregnant women were tested in this study,and 85 positive cases(6.4%)were screened out.One fetus was diagnosed as having Down's syndrome by detecting the chromosomes in the amniotic fluid.Conclusions The method of time-resolved fluoroimmunoassay through dried blood specimen,in place of the serum method,to detect the levels of AFP and β-hCG among mid-term pregnant women is convenient and feasible and its screening result is accurate and reliable.