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: Surgery
[{'content': 'Most common cause of abdominal aortic aneurysm is: \nSelect and explain. \nA. Trauma, B. Vsculitis, C. Syphilis, D. Atherosclerosis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: • “90% all abdominal aortic aneurysms are related to atherosclerotic disease and most of these aneurysms are below the level of renal arteries.”\n• Aneurysm: permanent and irreversible localized dilatation of blood vessel with at least 50% increase in diameter\n• Ectasia: dilatation <50% of normal diameter\n• AAA (abdominal aortic aneurysm) is diagnosed if diameter >3 cm in males or >2.6 cm in females\n• MC location: Aorta >Iliac >Popliteal >Femoral (AIPF)\n• MC site of extra-cranial arterial aneurysm is infrarenal aorta\n• MC site of peripheral aneurysm: Popliteal aneurysm\n• Degenerative aneurysms (caused by atherosclerosis) are MC AAA (90%)\n• Width of aneurysm is most important predicting factor of rupture.\n• Juan Parodi\xa0introduced endovascular aortic aneurysm repair (EVAR).\nClassification\n• True (all three layers of vessel are involved), false (do not have all three layers of vessel)\n• Infected (mycotic) aneurysm are false aneurysm\n• Dissecting aneurysm (dissection with aneurysmal dilatation of false lumen)\n• Fusiform (symmetrical enlargement involving whole circumference of artery)\n• Saccular (affect only part of the arterial circumference) have higher risk of rupture', 'role': 'assistant'}]