This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Most commonly detected genitourinary abnormality seen in first trimester ultrasound is ? \nSelect and explain. \nA. Megacystis, B. Hydronephrosis, C. Cystic Kidney, D. Renal Agenesis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most commonly detected genitourinary abnormality seen in first trimester ultrasound is megacystis. Megacystis is a sign of lower urinary tract obstruction , which have several causes. Fig1 - Megacystis in a male fetus at 13 weeks gestation Fig2 - Prune belly sequence by urethral obstruction sequence with megacystis', 'role': 'assistant'}]