This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetal circulation, Subject name: Pediatrics
[{'content': 'What is the commonest aneuploidy seen in neonates born with single umbilical aery? \nSelect and explain. \nA. Trisomy 18, B. Trisomy 13, C. Trisomy 21, D. Trisomy 15', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Single umbilical aery: - It is seen in 5-10/1,000 bihs & its frequency increases in twin bihs - 30% of these infants are associated with more than one congenital abnormalities; among which Trisomy 18 is most commonest - Though it is associated with increased risk for occult renal anomaly, if no other anomalies are present, need for renal USG is controversial', 'role': 'assistant'}]