Spina bifida is a neural tube defect - a type of birth defect of the brain, spine, or spinal cord. It happens if the spinal column of the fetus doesn 't close completely during the first month of pregnancy. This can damage the nerves and spinal cord. Screening tests during pregnancy can check for spina bifida. Sometimes it is discovered only after the baby is born. The symptoms of spina bifida vary from person to person. Most people with spina bifida are of normal intelligence. Some people need assistive devices such as braces, crutches, or wheelchairs. They may have learning difficulties, urinary and bowel problems, or hydrocephalus, a buildup of fluid in the brain. The exact cause of spina bifida is unknown. It seems to run in families.