This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
Which one of the following biochemical parameters is the most sensitive to detect open spina 
Select and explain. 
A. Maternal serum alpha fetoprotein, B. Amniotic fluid alpha fetoprotein, C. Amniotic fluid acetyl cholinesterase, D. Amniotic fluid glucohexaminase
C: Amniotic fluid acetyl cholinesterase
Answer: C: Amniotic fluid acetyl cholinesterase 
Explanation: Ans. is c i.e. Amniotic fluid acetyl cholinesterase Spina Bifida, anencephaly and encephalocele are collectively included under neural tube defect. As I have already explained in answer 3, amniotic fluid cholinesterase level is elevated in most cases of neural tube defects and has got better diagnostic value than AFP. Extra Edge : Ultrasonographic signs indicating Spina bifida. Small biparietal diameter. Ventriculomegaly. Frontal bone scalloping (the so called lemon sign).deg Elongation and downward displacement of the cerebellum (the so called banana sign).deg Effacement or obliteration of the cisterna magna.