羊水甲胎蛋白浓度与胎儿畸形的关系

The relationship between the level of amniotic fl uid alpha-fetoprotein and fetal malformation

目的了解羊水甲胎蛋白（AFP）浓度与胎儿畸形的关系。方法对2007年1月至2012年5月在本院进行羊膜腔穿刺的孕17～23w孕妇5262例，运用酶联免疫吸附法对羊水进行AFP检测，根据其2．5倍中位数倍数（MoM）值进行分组，观察孕妇的妊娠结局，分析羊水AFP升高与胎儿畸形的关系。结果1．各孕周羊水AFP的2．5MoM值分别为：孕17w 41150ng／ml，18w38395ng／ml，19w 34995ng／ml，20w 31700ng／ml，21w 29655ng／ml，22w 26940ng／ml，23w 21800ng／ml。2．羊水AFP≥2．5MoM时发生率明显升高的胎儿畸形为：神经管缺陷，颈部淋巴管瘤，死胎。结论羊水AFP≥2．5MoM时，临床诊断除考虑神经管缺陷，还应警惕是否有颈部淋巴管瘤或死胎可能。羊水AFP≥2．5MoM对于诊断神经管缺陷的特异度及阴性预测价值较高，但灵敏度及阳性预测价值一般，需结合系统彩超排除相关畸形。

Objective： To investigate the relationship between the level of amniotic fluid alpha-fetoprotein （AFP） and fetal malformation. Methods： A total of 5262 women were taken amniotic fluid sample for the measurement of alpha-fetoprotein by enzyme linked immunosorbent assay during 17 to 23 weeks of gestation from January 2007 to May 2012. According the level of 2.5 multiple of median （MoM） of AFP, we divided the women into two groups. In the end, the pregnancy outcome was record and analyzed. The difference of incidence of fetal malformation in the two groups was compared. Results： 1.The 2.5 MoM of amniotic fluid AFP in different gestational weeks are： 41150ng/ml in 17 weeks, 38395ng/ml in 18 weeks, 34995ng/ml in 19 weeks, 31700ng/ ml in 20 weeks, 28535ng/ml in 21 weeks, 24120ng/ml in 22 weeks, 20043ng/ml in 23 weeks. 2. The fetal malformations related to elevated amniotic fluid AFP were： neural tube defects （NTDs）, cystic hygroma, fetal demise. Conclusion： Except NTDs, cystic hygroma and fetal demise should be considered when amniotic fluid AFP≥2.5 MoM. Specificity and negative predictive value of anmiotie fluid AFP are quite high in diagnosis of NTDs, but sensitivity and positive predictive value are not high enough. Ultrasound should be needed for further diagnosis.