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
[{'content': 'Anencephaly is best diagnosed using: \nSelect and explain. \nA. Maternal serum alpha feto protein, B. Amniotic fluid alpha feto protein, C. USG, D. X-ray', 'role': 'user'}, {'content': 'Answer: C \nExplanation: “In the early days of AFP screening, an elevated maternal serum AFP level prompted amniocentesis to determine the amniotic fluid AFP level. If the AFP level was elevated, then an assay for acetylcholinesterase was done. These tests were considered diagnostic for fetal NTD. Today however nearly 100% of NTDs are identified by ultrasonography used alone.”\nDiagnosis of Anencephaly/NTD in brief:\n\nBest screening test for NTD: Maternal serum alpha protein (between 14 and 22 weeks, best at 16 weeks).\nBest marker for NTD/Open spina bifida/ Anencephaly is Acetylcholinesterase.\nBest investigation for Anencephaly—ultrasound.\nBest time for diagnosis of Anencephaly is ≥ 14 weeks by USG\nEarliest diagnosis of Anencephaly by 10 weeks.\nBest investigation for hydrocephalus is Ultrasound.', 'role': 'assistant'}]