Quantitative estimation of the density ratios of cholinesterase bands in human amniotic fluids.

Quantitative densitometry has been used to measure cholinesterase bands in amniotic fluids after polyacrylamide gel electrophoresis. The ratio of acetylcholinesterase (AChE) to pseudocholinesterase ( PChE ) could be used both for diagnosis and for differential diagnosis of fetal abnormalities. Normal amniotic fluids had AChe/ PChE density ratios of zero, while neural tube defect fluids were all above 0.15. Ventral wall defect samples had ratios below 0.15, as did false positives due to contamination with human fetal serum. In samples which had been accidentally contaminated with fetal calf serum, density ratios were above 0.15. Similar results were obtained with both slab gel and rod gel electrophoresis.