In medical terms, AAA stands for abdominal aortic aneurysm, a bulge or swelling in the aorta, the largest blood vessel in your body, where it passes through your abdomen. A normal aorta is about 2 centimeters wide. When that section balloons to 3 centimeters or more, it’s classified as an aneurysm. Most AAAs produce no symptoms at all and are discovered by accident during imaging for something else, but a rupture is a life-threatening emergency with roughly a 50% mortality rate even with surgery.
Where It Happens and Why It Matters
Your aorta runs from your heart down through your chest and into your abdomen, where it splits into two branches supplying your legs. The abdominal section, below your kidneys, is where aneurysms most commonly form. Over time, the wall of the aorta weakens and stretches outward like a worn spot on a tire. The danger isn’t the bulge itself but the risk that it will tear or burst, causing massive internal bleeding.
Who Is Most at Risk
Smoking is the single biggest risk factor. In major clinical trials, over 90% of patients with AAA were current or former smokers. For screening purposes, “ever smoked” is defined as having smoked 100 or more cigarettes in your lifetime. Male sex is the other major factor: men develop AAAs far more often than women.
Genetics play a meaningful role too. About 13% of people diagnosed with AAA have a first-degree relative (parent, sibling, or child) with the same condition. Twin studies put the genetic contribution into sharper focus: if one identical twin has an AAA, the other twin’s risk is about 24%, roughly 71 times higher than the general population. Atherosclerosis (plaque buildup in arteries), high blood pressure, and abdominal obesity round out the list of established risk factors.
Symptoms of an Intact AAA
Most abdominal aortic aneurysms are completely silent. You could have one for years without knowing. When symptoms do appear, they usually mean the aneurysm is growing or pressing on nearby structures. Common signs include deep, constant pain in the belly or side, persistent back pain, and a throbbing or pulsing sensation near the belly button. Some people actually feel or see a pulsation in their abdomen.
Less obvious symptoms can include early fullness after eating, nausea, urinary problems, or groin pain. Groin pain is particularly tricky because it doesn’t point to the abdomen, making misdiagnosis more likely. In rare cases, a clot forms inside the aneurysm and blocks blood flow to the legs, causing sudden pain, weakness, or numbness.
What a Rupture Looks Like
A ruptured AAA causes sudden, severe pain in the abdomen or back that patients often describe as ripping or tearing. This is typically accompanied by a rapid pulse and a drop in blood pressure. In severe cases, a person may become pale, confused, or lose consciousness. The classic combination of pain, low blood pressure, and a pulsatile abdominal mass is actually present in fewer than half of rupture cases, which is one reason ruptured AAAs are sometimes initially misdiagnosed as kidney stones, back problems, or other conditions.
In-hospital mortality for ruptured AAA treated with open surgery is around 48.5%, a figure that has not improved significantly over decades. Many additional patients die before reaching the hospital, making the total mortality rate even higher. This is why early detection matters so much.
Screening Recommendations
The U.S. Preventive Services Task Force recommends a one-time abdominal ultrasound screening for men aged 65 to 75 who have ever smoked. For men in the same age range who have never smoked, screening is offered selectively based on other risk factors. Routine screening is not recommended for women who have never smoked and have no family history of AAA. For women who have smoked or have a family history, the evidence is currently considered insufficient to make a firm recommendation either way.
The screening itself is simple and painless: an ultrasound of your abdomen that takes a few minutes.
How a Small AAA Is Monitored
If an aneurysm is found but isn’t large enough for surgery, you enter a surveillance program. On average, AAAs grow about 2.6 millimeters per year, but individual rates vary widely. Some barely grow at all; others expand much faster.
Surveillance intervals are based on current size. For an aneurysm around 3.5 centimeters, a follow-up ultrasound every 3 years is typical. At 4 centimeters, that tightens to every 2 years. At 4.5 centimeters, annual imaging is recommended. Once the aneurysm reaches 5 centimeters, checks every 3 months keep close watch as it approaches the size where repair is considered. These intervals are designed to keep the chance of unexpectedly reaching the surgical threshold below 1%.
When Surgery Is Recommended
The widely accepted threshold for surgical repair is 5.5 centimeters for men and 5.0 centimeters for women. These thresholds are endorsed by both the Society for Vascular Surgery and the European Society for Vascular Surgery. Rapid growth (more than 1 centimeter per year) or the development of symptoms can also trigger a recommendation for repair at smaller sizes.
Some recent research suggests that these historical thresholds may be more conservative than necessary for certain patients. One analysis found that for a 60-year-old man in average health, the optimal size to minimize aneurysm-related death was actually closer to 6.9 centimeters, and for a 60-year-old woman, about 6.1 centimeters. These findings are prompting ongoing discussion about tailoring thresholds to individual risk profiles rather than using a single cutoff.
Repair Options: Open Surgery vs. EVAR
Two main procedures exist for AAA repair. Open surgery involves making a large incision in the abdomen, clamping the aorta above and below the aneurysm, and replacing the damaged section with a synthetic graft. It’s a major operation with a longer recovery, but the repair tends to be very durable over time.
The less invasive option, called EVAR (endovascular aneurysm repair), involves threading a stent graft through small incisions in the groin arteries and positioning it inside the aneurysm to redirect blood flow away from the weakened wall. Recovery is significantly faster, and the 30-day mortality rate is about 1.4% compared to 4.2% for open repair, a 67% reduction.
That early survival advantage doesn’t last forever, though. Beyond about 8 years, EVAR patients actually show higher rates of both overall and aneurysm-related death, partly because the stent grafts can develop leaks or other complications that require additional procedures. EVAR patients need lifelong imaging surveillance to catch these issues. For this reason, younger patients with a longer life expectancy and lower surgical risk often benefit more from open repair, while EVAR is frequently preferred for older patients or those with significant health problems that make major surgery riskier.