An abdominal aortic aneurysm is defined as any enlargement of the abdominal aorta - the main artery running through the abdomen.

Most abdominal aortic aneurysms are small and do not pose a health problem.

However, if the enlarged blood vessel begins to leak blood or ruptures, it will typically cause severe, unremitting abdominal and lower back pain and is a serious medical emergency requiring emergency surgery.

A prominent symptom of an abdominal aortic aneurysm that has ruptured is severe, constant lower back pain and abdominal pain.