Strategies for Prevention of Neural Tube Defects

Neural tube defects (NTDs) are congenital malformations of the brain and spinal cord caused by the failure of neural tubes to close between 21 and 28 days after conception (Sadler, 2005). Any disruption of neurulation during or prior to this time may result in a defect or failure of neural tube closure. Non-invasive prenatal diagnostic testing by ultrasound and maternal serum screening, which should be offered at 16 to 20 weeks gestation and 15 to 20 weeks gestation, respectively, will identify 95% of spina bifida and 100% of anencephaly cases. After 15 weeks of pregnancy, invasive prenatal diagnostic testing with ultrasound-guided amniocentesis can evaluate the fetal karyotype and measure amniotic fluid alpha-fetoprotein and acetylcholinesterase, to assist in differentiating between open or closed lesions (Chodirker et.al., 2001). The majority of cases can be categorized as either anencephaly (lack of closure in the region of the head) or spina bifida (lack of closure below the head).