Abdominal Aortic Aneurysm (AAA)
What Is an Abdominal Aortic Aneurysm?
An abdominal aortic aneurysm (AAA) is a localized enlargement or bulging in the abdominal portion of the aorta, the largest artery in the body that carries oxygenated blood from the heart to the abdomen, pelvis, and legs. This bulge occurs when the aortic wall becomes weakened and expands beyond its normal diameter — generally defined as 50% larger than normal or greater than 3 cm — and can grow slowly over many years without symptoms.
AAAs are sometimes called the “silent killer” because they often produce no symptoms until they become large or begin to rupture. In some cases, patients may notice a pulsating sensation in the belly, deep abdominal or back pain, or discomfort in the flank or legs. Rupture of an AAA is a medical emergency that can cause life‑threatening internal bleeding and requires immediate hospital care.
Causes and Risk Factors
The exact cause of an AAA isn’t fully understood, but several factors weaken the aortic wall and increase the risk of aneurysm formation, including:
- Atherosclerosis (hardening of the arteries), the most common factor
- Smoking and tobacco use
- High blood pressure (hypertension)
- Male sex and advancing age (most often over 60)
- Family history of aneurysms
- Connective tissue disorders such as Marfan syndrome or Ehlers‑Danlos syndrome
Other contributors can include chronic inflammation, infection, and traumatic injury to the aorta. Because AAAs typically develop gradually, they may not be detected until imaging is done for another reason or they reach a size that prompts screening.
How an AAA Is Diagnosed
Diagnosing an abdominal aortic aneurysm often begins with a physical exam, where a clinician may detect a pulsating abdominal mass or abnormal sounds called a bruit. Confirmatory testing generally includes:
- Abdominal ultrasound — the most common screening tool
- CT scan (computed tomography) — provides detailed images of the aneurysm’s size and location
- MRI / MRA — alternative imaging in select cases
Regular screening with abdominal ultrasound is recommended for men ages 65–75 who have ever smoked, and may be considered earlier for individuals with a strong family history or other risk factors.
Treatment Options
The course of treatment depends on the size and growth rate of the aneurysm, as well as symptoms:
- Watchful waiting and regular imaging for small, asymptomatic AAAs
- Endovascular aneurysm repair (EVAR) for suitable aneurysms — a minimally invasive procedure placing a stent graft inside the aorta to reinforce the weakened wall
- Open surgical repair — traditional open surgery to replace the aneurysmal section with a graft, typically used when EVAR isn’t feasible
Large aneurysms (often >5.5 cm) or those that are rapidly growing or symptomatic are typically recommended for repair to prevent rupture.
