Neural Tube Defects Workup

Updated: Nov 26, 2018
  • Author: Nir Shimony, MD; Chief Editor: Amy Kao, MD  more...
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Workup

Imaging Studies

Ultrasonography is used antenatally for neural tube defect (NTD) screening. All pregnant women should be offered screening for NTDs via ultrasound. Postnatally, its role has been limited because of advances in other imaging modalities. It is also helpful for quickly screening for hydrocephalus.

MRI is the study of choice for imaging neural tissue and for identifying contents of the defect in the newborn. This is not routinely performed in the neonate unless unusual deficits not associated with the open defect are present. This allows for visualization of associated anomalies, both intraspinal and intracranial.

CT scan allows direct visualization of the bony defect and anatomy. This study is also used to determine the presence or absence of hydrocephalus or other intracranial anomalies, although exposure of young children to radiation from CT studies should be considered. Hence, the use of CT scan is usually reserved for adults or older kids with spina bifida occulta. 

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Laboratory Studies

Maternal serum alpha-fetoprotein can be measured in maternal serum (MSAFP), amniotic fluid, and fetal plasma. It is typically measured around 16–18 weeks' gestation. MSAFP is a fetal-specific protein synthesized by the fetal yolk sac, GI tract, and liver. Interpretation of results varies by institution, but typically levels 2–2.5-fold above average (for a particular gestational age) is considered abnormal. However, many factors, both fetal and maternal, can affect interpretation of results. Abnormal MSAFP tests are typically followed by an ultrasound exam to assess for possible NTD, confirm gestational age, fetal viability, number of fetuses, and so on.   

Genetic counseling and further testing with amniocentesis may be indicated for equivocal MSAFP and ultrasound findings. 

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