What is an AAA?
An abdominal aortic aneurysm is a widening, or dilation, of the abdominal aorta to approximately 2 to 2.5 times its normal size. The majority of AAAs are infrarenal, or below the kidneys. They may also occur juxtarenal (near the kidneys), pararenal (around the kidneys), or suprarenal (above the kidneys).
The size of the AAA generally reveals the danger involved. Abdominal aortic aneurysms that are less than 3.5cm in diameter are usually not dangerous; however, all aneurysms must be watched carefully as rapid growth can occur at any point.
Once an AAA becomes symptomatic, the risk of impending rupture is high, and immediate surgery is required to prevent rupture and prolong the life of the patient. If a physician fails to recognize these risk factors, or fails to operate on a symptomatic AAA, the mortality rate of the patient increases from approximately 30% at 30 days, to approximately 80% at one year. Therefore, it is important that a physician know the risk factors for impending rupture, and be ready to operate immediately if needed.
Risk Factors of a Symptomatic AAA
Once an AAA becomes symptomatic, there are risk factors involved that give warning to impending rupture of the aneurysm. These include the following:
1. Size and growth rate of the aneurysm: An aneurysm greater than 4cm should raise concern for possible impending rupture.
2. Expansion: If the aneurysm has suddenly expanded, the risk for rupture is also increased.
3. Blood pressure: Elevated blood pressure can cause the AAA to expand and become painful, signaling possible impending rupture.
4. Acute abdominal and/or back and flank pain: Sudden pain in these areas is a significant risk for rupture of the aneurysm.
5. Change in condition: A sudden change in the patient’s pain or tenderness should raise further concern for the possibility of rupture.
6. Tenderness: Tenderness results from expansion of the aneurysm, and warrants further evaluation of possible rupture.
Additionally, the more risk factors present in the patient, the greater risk of rupture and greater need for emergent surgery.
Signs and Symptoms That an AAA Has Ruptured
In patients who experience any or all of the above risk factors, evaluation of the aneurysm should be done immediately. Leakage of the aneurysm noted on CAT scan indicates rupture has occurred, as well as the presence of hypotension and low blood count. If any of these signs are present, immediate surgical intervention is required.
Treatment for Symptomatic Abdominal Aortic Aneurysms
Even small aneurysms can suddenly grow rapidly. If a patient is a poor surgical candidate, and has an aneurysm less than 4cm in diameter, the physician may choose careful observation rather than surgery. However, if the aneurysm is greater than 6cm, surgical resection is indicated. In a good-risk patient, any aneurysm greater than 4cm warrants surgical resection.
Death caused from an abdominal aortic aneurysm is usually due to rupture, with the mortality rate for ruptured aneurysms as high as 50% to 70%. Therefore, when an AAA becomes symptomatic and risk factors for rupture are present, and/or signs of rupture, emergency surgery is indicated.
Awareness is key to diagnosis of a dangerous abdominal aortic aneurysm. Although most AAAs are symptom free, expansion can occur quickly, raising the risk of impending rupture. Recognizing the characteristics of a symptomatic AAA can save your life.
Choose your healthcare provider wisely to assure that they are using due care in evaluating and monitoring your individual situation, and are ready to perform emergency surgery if required.