The aorta is the largest blood vessel in the body and it transports oxygen and nutrients in the blood to the rest of the body's organs. A small aortic aneurysm poses little risk and can simply be monitored. If however, the aneurysm grows to more than 5.5cm in diameter, there is a higher risk of rupture and massive internal bleeding. This is very uncommon (1 in 10,000) but is an extreme life-threatening condition. The actual prevalence of aortic aneurysms is approximately 6 in 100 men and 2 in 100 women aged over 65. The following diagram illustrates an aortic aneurysm.