screening for neural tube defects
Last reviewed 01/2018
In 95% of cases of anencephaly or open meningomyelocoele, an increase in amniotic alpha-feto protein can be detected by the fifth month of pregnancy. Early termination can then be offered to the parents. False negatives occur in 0.5% of cases; false positives, in 2%. There is also an increase in amniotic acetylcholinesterase. High resolution ultrasound should be used to confirm the biochemical results.
Initially amniocentesis and estimation of alpha-feto protein was only considered in couples who had an affected child. However it has become apparent that maternal serum levels of alpha-feto protein are also raised in many cases of neural tube defect and screening of all mothers, irrespective of previous history may be undertaken.