(rachischisis) a developmental defect in which the newborn baby has part of the spinal cord and its coverings exposed through a gap in the backbone. The symptoms may include paralysis of the legs, incontinence, and learning disabilities from the commonly associated brain defect, *hydrocephalus. Spina bifida is associated with an abnormally high level of *alpha-fetoprotein in the amniotic fluid surrounding the embryo. The condition can be diagnosed at about the 16th week of pregnancy by a maternal blood test and confirmed by amniocentesis and ultrasound. The risk of spina bifida is reduced if supplements of *folic acid are taken by women while trying to conceive and during the first three months of pregnancy. See also neural tube defects.... spina bifida
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