How do health care providers diagnose neural tube defects (NTDs)?

NTDs are usually diagnosed during pregnancy, through laboratory or imaging tests.

Prenatal laboratory tests may include:

• “Triple screen” blood test: One part of the triple screen blood test looks for an elevated level of alpha-fetoprotein (AFP), which is associated with a higher risk of NTDs. The AFP test also can be done by itself. The two other parts of the triple screen involve testing for human chorionic gonadotropin (hCG) and estriol. This test generally is done during the second trimester.¹
• Amniotic fluid tests: Testing amniotic fluid may also show a high level of AFP, as well as high levels of acetylcholinesterase. Health care providers might perform this test to confirm high levels of AFP seen in the triple screen blood test. The amniotic fluid also can be tested for chromosomal abnormalities, which might also be the cause of the abnormal AFP level.²

Prenatal ultrasound imaging usually detects almost all types of NTDs.²

Shortly after the birth of an infant with a diagnosed or suspected NTD, the health care provider will perform tests to assess the severity of the NTD and any complications. These tests might include an X-ray, magnetic resonance imaging (MRI), a computed tomography (CT or CAT) scan to look for spinal defects or excess fluid2; measuring the head circumference; assessing the infant’s strength, motor, and sensory functioning; and observing the infant’s urinary stream.³

Those with milder spina bifida may not be diagnosed until later in childhood or in adulthood.²