This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in Obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Investigation of Choice post datism? \nSelect and explain. \nA. USG, B. Xray, C. Amniocentesis, D. Spectrophotometry', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) USGREF: Dutta 6th edp. 319Post dated pregnancy: (> 2weeks beyond the expected date of delivery (gestational age > 294 days)Etiology:Wrong dates : most commonHereditaryPrimi, sedentary habit, previous prolonged pregnancy, elderly multiparaFetal congenital anomalies like anencephalyPlacental sulphatase deficiencyClinical diagnosis:Menstrual historyWeight recordAbdominal girthHeight of uterus , uterus feels full of fetus , hard bones of fetusRipe cervixInvestigations:Assessment of fetal maturity:[?] USG: it is the investigation of choice[?] FL, CRL, BPD are measured and composite biometry done[?] Amniocentesis is invasive, and has been replaced by USG.Assessment of well being:[?] Modified biophysical profile[?] Absence of umbilical artery end diastolic frequency indicates fetal jeopardy.', 'role': 'assistant'}]