This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Impoant Genetic Syndromes, Subject name: Pediatrics
[{'content': 'Among the following, the most sensitive antenatal USG finding of Trisomy 21 is: \nSelect and explain. \nA. Absent nasal bone, B. Thickened nuchal fold, C. Sho femur, D. Echogenic bowel', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Prenatal USG markers of Down syndrome- Thickness of nuchal fold (75% sensitive) Absence of nasal bone (58% sensitive) cardiac abnormalities, duodenal atresia, shoened femur, shoened humerus, echogenic bowel', 'role': 'assistant'}]