Most useful maternal serum test used for distinguishing open neural tube defects and ventral wall defect in a fetus?

Acetylcholinesterase is derived mostly from the tissues of the fetal nervous system. Amniotic fluid acetylcholinesterase is a biochemical marker that is positive in 95% fetuses with open neural tube defects. When both AFP and AChE is positive, likelihood of an open spine defect is greater than 99.5%. High acetylcholinesterase and low butrylcholinesterase in seen in open neural tube defect. Opposite occur in open ventral wall defect. Ref: Clinical Laboratory Medicine By Kenneth D. McClatchey, 2nd Edition, Page 644 ; Genetic Disorders and The Fetus: Diagnosis, Prevention and Treatment Edited By Aubrey Milunsky, 6th Edition ; Diseases of The Liver and Biliary System in Children By Deirdre A. Kelly, 3rd Edition, Page 306 ; Fundamentals of Surgical Practice By A. N. Kingsnoh, 2nd Edition, Page 172