How Is SB Diagnosed?

In most instances, SB is diagnosed either prenatally or postnatally (just after birth). When the diagnosis is made while the baby is still in utero, it is usually through screening tests during the 2nd trimester, the maternal serum alpha-fetoprotein (AFP) blood test and ultrasound. Because AFP blood test is not precise and does not screen exclusively for SB, it is not the sole diagnostic tool for prenatally diagnosing SB. If the AFP blood test is high, additional tests such as an amniocentesis will be completed.

When SB is not identified prenatally, it may be detected when hydrocephalus is diagnosed (SB and hydrocephalus occur together in several cases). Also, X-rays may discover mild cases of SB during a routine examination. In the cases of more severe SB, weakness in the feet, hips, or legs may be reported and therefore prompt further diagnosis.