Quick answer
An aortic aneurysm is a bulge in the wall of your aorta, the large vessel carrying blood from your heart to the rest of your body. It counts as an aneurysm once the aorta widens past one and a half times normal size. One in your belly is called abdominal, one in your chest thoracic. Most cause no symptoms. The worry is that the bulge can tear or rupture.
An aortic aneurysm is an enlargement (dilation) of the aorta to greater than 1.5 times normal size. They usually cause no symptoms except when ruptured. Occasionally, there may be abdominal, back, or leg pain.
What is an aortic aneurysm?
An aortic aneurysm is an abnormal bulge that occurs in the wall of the major blood vessel (aorta) that carries blood from your heart to your body. Aortic aneurysms can occur anywhere in your aorta and may be tube-shaped (fusiform) or round (saccular). Aortic aneurysms that pass through the abdomen are called abdominal aortic aneurysms, while those that pass through the chest cavity are called thoracic aortic aneurysms. Having an aortic aneurysm increases your risk of developing an aortic dissection or rupture.

