<prompt> Which one of the following biochemical parameters is the most sensitive to detect open spina bifida?Maternal serum alpha fetoprotein.Amniotic fluid alpha fetoprotein.Amniotic fluid acetyl cholinesterase.Amniotic fluid glucohexaminase.  <response>: Detection of NTD most specific test: ACE acetylcholinesterase most sensitive test: AFP alfa feto protein Neural tube defects can be distinguished from other fetal defects e.g. abdominal wall defects by use of the acetylcholinesterase test performed on amniotic fluid obtained by amniocentesis Acetylcholinesterase elevated along with AFP then a neural tube defect is likely. The Acetylcholinesterase level elevation is specific for the NTDs and if it is not elevated in presence of an elevated AFP, then a defect other then neural tube defect is suggested. 