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': 'Which one of the following congenital malformation of the fetus can be diagnosed in first trimester by ultrasound ? \nSelect and explain. \nA. Anencephaly, B. Inencephaly, C. Microcephaly, D. Holoprosencephaly', 'role': 'user'}, {'content': 'Answer: A \nExplanation: As discussed in chapter on fetal malformation, anencephaly can be diagnosed as early as 8-10 weeks/first trimester in experienced hards.\nMicrocephaly:\nUSG in Obs and Gynae Callen 4/e, p 298, 299\n\nIt is decreased head size.\nIn these patients both brain mass and total cell number are reduced.\nThere is disproportion in size between the skull and face.\nIt is difficult to recognize this anomaly by ultrasound – A head circumference below 2 SD from the mean is used as a diagnostic criteria in midtrimester scan.\n\nHoloprosencephaly is the presence of a single centrally placed cerebral ventricle and may be associated with midline abnormalities of the face.\nWith the use of vaginal probe it can be recognised in the beginning of midtrimester.', 'role': 'assistant'}]