Spina Bifida Diagnosis
In most cases, spina bifida is diagnosed prenatally, or before birth. However, some mild
cases may go unnoticed until after birth, or postnatally. Very mild cases, in which there
are no symptoms, may never be detected.
Prenatal Diagnosis of Spina Bifida
The most common screening methods used to look for spina bifida during
pregnancy are second trimester maternal serum alpha fetoprotein (MSAFP) screening and
fetal ultrasound. The MSAFP screen measures the level of a protein called
alpha-fetoprotein (AFP), which is made naturally by the fetus and placenta. During
pregnancy, a small amount of AFP normally crosses the placenta and enters the
mothers bloodstream. But if abnormally high levels of this protein appear in the
mothers bloodstream it may indicate that the fetus has a neural tube defect. The
MSAFP test, however, is not specific for spina bifida, and the test cannot definitively
determine that there is a problem with the fetus. If a high level of AFP is detected, the
doctor may request additional testing, such as an ultrasound or amniocentesis to help
determine the cause.
The second trimester MSAFP screen described above may be performed alone or as part of a
larger, multiple-marker screen. Multiple-marker screens look not only for neural tube
defects, but also for other birth defects, including Down syndrome and other chromosomal
abnormalities. First trimester screens for chromosomal abnormalities also exist but signs
of spina bifida are not evident until the second trimester when the MSAFP screening is
Amniocentesisan exam in which the doctor removes samples of fluid from the amniotic
sac that surrounds the fetusmay also be used to diagnose spina bifida. Although
amniocentesis cannot reveal the severity of spina bifida, finding high levels of AFP may
indicate that the disorder is present.
Postnatal Diagnosis of Spina Bifida
Mild cases of spina bifida not diagnosed during prenatal testing may be
detected postnatally by X-ray during a routine examination. Doctors may use magnetic
resonance imaging (MRI) or a computed tomography (CT) scan to get a clearer view of the
spine and vertebrae. Individuals with the more severe forms of spina bifida often have
muscle weakness in their feet, hips, and legs. If hydrocephalus is suspected, the doctor
may request a CT scan and/or X-ray of the skull to look for extra fluid inside the brain.