An aortic aneurysm is a weak area in the aorta, the main blood vessel that carries blood from the heart to the rest of the body. As blood flows through the aorta, the weak area bulges like a balloon and can burst if the balloon gets too big. A small aneurysm may require no immediate treatment other than “watchful waiting” - checking the aneurysm with CT scanning or an Ultrasound regularly to be certain it does not grow. If an aneurysm reaches a certain size, however, there is danger that it will burst and bleed uncontrollably (hemorrhage). In these cases treatment is necessary.