False positive gel-acetylcholinesterase results in blood-stained amniotic fluids.
The effect of blood contamination on the gel-acetylcholinesterase (AChE) test used in the diagnosis of fetal open neural-tube defects was studied with amniotic fluid samples artificially contaminated with fetal or maternal blood in concentrations covering a range exceeding that usually found in clinical practice. Amniotic fluid samples contaminated with maternal blood gave negative gel-AChE results at all concentrations. Contamination with fetal blood yielded positive results if the erythrocyte concentration was greater than about 60 x 10(6) cells/ml. Thus contamination of amniotic fluid with blood is only likely to cause false positive gel-AChE results if this critical concentration is exceeded. Such samples will occur only rarely in clinical practice but when they do the diagnosis should be made with caution.
D000110:Acetylcholinesterase / Q000032:analysis*; D000653:Amniotic Fluid / Q000201:enzymology*; D001769:Blood; D004591:Electrophoresis, Polyacrylamide Gel; D004906:Erythrocyte Count; D005189:False Positive Reactions; D005260:Female; D005312:Fetal Blood; D006400:Hematocrit; D006801:Humans; D009436:Neural Tube Defects / Q000175:diagnosis*; D011247:Pregnancy; D011296:Prenatal Diagnosis
D000110:Acetylcholinesterase