Wald N J, Kennard A
Wolfson Institute of Preventive Medicine, Medical College of St. Bartholomew's Hospital, London, UK.
Curr Opin Obstet Gynecol. 1992 Apr;4(2):302-7.
Antenatal serum screening for Down's syndrome is now becoming established in many centers throughout the world. The screening method is based on the measurement of alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin between 15 and 22 weeks of pregnancy. These measurements, used in conjunction with a woman's age, provide risk estimates of having a pregnancy with Down's syndrome for every woman screened. By identifying the 5% of women with highest risk and offering them an amniocentesis, about 60% of Down's syndrome pregnancies can be identified. If an ultrasound scan examination is used routinely to estimate gestational age, the detection rate can be increased by 5% to 10%. Recent information on the distribution of the three serum markers in twin pregnancies and pregnancies with insulin-dependent diabetes mellitus now means that screening can be carried out in such pregnancies. Various other serum markers of Down's syndrome have been reported, but at present they do not have a place in routine antenatal screening for Down's syndrome. The role of amniotic fluid acetylcholinesterase measurement, alone and in combination with amniotic fluid alpha-fetoprotein measurement, in the antenatal diagnosis of open neural tube defects has recently been clarified. The best policy is to perform an amniotic fluid alpha-fetoprotein measurement as the primary test and an acetylcholinesterase determination for those women who have an amniotic fluid alpha-fetoprotein measurement of two times the normal median or greater. The acetylcholinesterase can be measured either by the standard method (gel electrophoresis) or by a new quantitative monoclonal antibody method.
目前，唐氏综合征的产前血清筛查在全球许多医疗中心已逐渐确立。筛查方法是基于在妊娠15至22周期间测量甲胎蛋白、游离雌三醇和人绒毛膜促性腺激素。这些测量结果与孕妇年龄相结合，可为每位接受筛查的孕妇提供怀有唐氏综合征胎儿的风险评估。通过识别出风险最高的5%的孕妇并为她们提供羊膜穿刺术，大约60%的唐氏综合征妊娠能够被识别出来。如果常规使用超声扫描检查来估算孕周，检出率可提高5%至10%。最近有关双胎妊娠和胰岛素依赖型糖尿病妊娠中这三种血清标志物分布的信息，意味着现在可以对这类妊娠进行筛查。已经报道了唐氏综合征的各种其他血清标志物，但目前它们在唐氏综合征的常规产前筛查中并无用武之地。羊水乙酰胆碱酯酶测量单独及与羊水甲胎蛋白测量联合在开放性神经管缺陷产前诊断中的作用，最近已得到明确。最佳策略是将羊水甲胎蛋白测量作为主要检测方法，对于羊水甲胎蛋白测量值为正常中位数两倍或更高的孕妇进行乙酰胆碱酯酶测定。乙酰胆碱酯酶可以通过标准方法（凝胶电泳）或新的定量单克隆抗体方法进行测量。
