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Letter: Routine alpha-fetoprotein studies in amniotic fluid.


 Alpha fetoprotein (AFP) assay of 500 amniotic fluid (AF) specimens was performed by rocket antigen-antibody electrophoresis, and the results were related to the WHO reference serum 72/225. Results obtained in 272 second trimester pregnancies known to have resulted in a normal infant are given tabularly; beyond 34 weeks, all pregnancies resulting in a normal infant had levels below 250 nanounits/ml, and abnormal results were obtained in 9 cases. These are briefly described. In all cases in which there was an abnormal AF AFP there was a severe fetal abnormality, although not necessarily a neural tube defect. In 1 case, the absence of AFP was associated with the absence of fetus. In another, the elevated AFP may have been associated with impending fetal death, rather than the abdominal wall defect found. In yet another case, the elevated third trimester AFP seemed obviously associated with impairment of fetal clearance of AF. As yet, no false positive results have been found, though not all the women studied have given birth. All AF samples should be assayed for AFP.
