An abdominal aortic aneurysm (AAA) represents a localized dilation of the largest blood vessel in the lower part of the body, which supplies blood to the legs. With increasing age of the population, the incidence of AAA rises sharply. The incidence of AAA is approximately 50 to 55 per 100,000 per year in men aged 55 to 64 years and nearly ten times that number in men over 80 years.

Anatomy and Pathology

• The aorta is the largest blood vessel in the body
  
• It begins at the heart and passes backward to be located deep in the body just in front of the bony spine
  
• When it passes through an opening in the diaphragm it becomes the abdominal aorta
  
• As the aorta passes into the pelvis it splits into the common iliac arteries
  
• The most important branches of the abdominal aorta feed the kidneys and bowel. (Figure 1)
  

Figure 1 - Anatomy showing the abdominal aorta and its branches. The abdominal aorta extends from the diaphragm to the iliac vessels. The branches feed the organs within the abdominal cavity.