An aortic aneurysm is defined as a widening of the aorta by >50% of its normal width. The aneurysm can involve the thoracic, abdominal or thoracoabdominal segments of the aorta. More than 90% of all aortic aneurysms occur in the infrarenal segment. They are found in 4.4% of the population over 40 years of age, 3-8 times more common in men.