Spina bifida refers to an opening on the baby's spine which exposes the spinal cord and can cause paralysis and other problems. Spina Bifida defects can be quite small, almost pinpoint in size, or much larger opening (grapefruit size). In 5% of cases, the opening is covered with skin, thus making it more difficult to diagnose. The most common problem seen in spina bifida is damage to the nerves as they are exposed to the amniotic fluid in the developing fetus. This damage may cause the baby to have weak or totally paralyzed legs. It may also cause a loss of feeling in the legs and loss of bladder or bowel control. If the skin opening is not covered, infection is always a concern, often requiring immediate surgery. Blockage can occur in the flow of spinal fluid at the lesion, leading to a buildup of fluid on the brain (hydrocephalus). This excessive fluid and subsequent pressure on the brain can cause further damage, so surgical shunting is required.