Aortic aneurysms often produce no symptoms, but in younger adults, abdominal aortic aneurysms may cause abdominal or lower back pain. Also, the area around the abdominal aortic aneurysm may be sensitive to the touch, or there may be a pulsing mass in the abdomen. Aortic aneurysms are easier to detect in thin people.

If a thoracic aortic aneurysm causes any symptoms, they may include:

However, the most obvious symptoms associated with aneurysms occur after a rupture. In this case, the aneurysm bursts, resulting in massive internal bleeding, often accompanied by sudden and extreme abdominal or back pain. There may also be a pulsing mass in the abdomen. Blood pressure will drop drastically, leading to symptoms of hypotension (e.g., dizziness, weakness, blurred vision or nausea). Rupture is an exceptionally dangerous event, and more than half of patients will die before they reach an emergency room.

The risk of rupture is related to three elements:

• The size of the aneurysm. Studies have shown a relatively low risk of rupture for abdominal aortic aneurysms less than 4 centimeters (about 1.5 inches), and between 4 to 7 centimeters for thoracic aortic aneurysms, depending on where they are located.
  
  
• The growth rate of the aneurysms. Some aneurysms remain relatively stable for a long period, then begin to grow rapidly. Others grow at a fairly consistent pace of half a centimeter annually. Aneurysms that grow more rapidly are more dangerous than slow-growing ones.
  
  
• The presence of symptoms. Studies have shown that aneurysms that cause pain or other symptoms are more likely to rupture than asymptomatic (without symptoms) aneurysms.

Aortic dissection is a condition in which there is an internal rupture of the innermost layers of the aorta that may form within the aneurysmal region. This represents a serious condition that precedes complete rupture of the aorta into the body space or into another organ such as the lungs or the trachea. One of the most serious types of rupture may occur within the pericardium (the membrane around the heart) in some patients. The resulting hemorrhage into the pericardial space impairs heart filling and can result in death unless surgical intervention is made. Therefore, the presence of a dissection flap in the proximal aorta is an indication for surgery regardless of the size of the aneurysm or the associated symptoms.