[Amniotic fluid acetylcholinesterase and prenatal diagnosis of neural tube defects. II. Qualitative test]

Abstract

The qualitative acetylcholinesterase (AChE) test has been used in conjunction with alpha-fetoprotein (AFP) assay on 255 amniotic fluid samples: 191 from normal pregnancies, 44 from abnormal pregnancies (foetal anomalies or intrauterine death). In all cases of normal amniotic fluid obtained before 25 weeks, gel revealed a single major band of non specific cholinesterase, even in fluids contaminated by maternal of foetal blood, whereas 5 fluids contaminated by foetal blood were false positive on AFP. In 8 normal specimens with clear aspect, obtained after 25 weeks, gel revealed a second (AChE) faint band, inhibited by BW 284 C 51. That result shows the risk of false-positive for samples obtained in late pregnancy. All 20 cases of neural tube defect gave a characteristic AChE band: large and intense band. In 9 cases of abdominal wall defect, 3 presented an AChE faint band, just as 2 cases of atresia and 2 cases of hydronephrosis. Negative AChE results were found un 1 case of congenital nephrosis, 3 cases of hydrocephaly and 1 case of teratoma. The main value of qualitative AChE test seems today in diagnosing neural tube defects with a greater sensibility and in classifying bloody fluids in which the AFP is at or above the cut-off level.