90% of spina bifida cases are discovered during an ultrasound before 18 weeks of pregnancy. Diagnosis is commonly done through a blood screening to test for alpha-fetoprotein (AFP) in the mother’s blood. Babies create this AFP protein that commonly reaches the mother’s bloodstream, but if the level of AFP is too high it could be a sign of spina bifida.

To determine the reason for high levels of AFP, a doctor will have an ultrasound done to confirm the reason. If further testing is needed, a doctor can perform an amniocentesis test in which a part of the amniotic fluid surrounding the baby is tested. If that fluid has a high concentration of AFP as well, it could be because the skin that should cover the spinal cord is not there and is causing a leakage of the baby’s spinal fluid.

MRI and CT scans are also possible tools for post-natal diagnosis.