Abdominal aortic aneurysm

An abdominal aortic aneurysm is an enlarged, weakened area in the lower part of the aorta, the major blood vessel that carries blood from the heart through the chest and abdomen. The aorta is the largest artery in the body. When a segment of its wall becomes weak, the pressure of blood flowing through it can cause the wall to bulge outward like a balloon.

Most abdominal aortic aneurysms develop slowly over many years and often cause no symptoms until they become large or rupture. A ruptured abdominal aortic aneurysm is a life-threatening emergency that causes massive internal bleeding and requires immediate surgery. Many aneurysms remain small and never rupture; others grow steadily and eventually need repair.

The goal of care is to detect aneurysms early through screening when appropriate, monitor those that are small, and repair larger or rapidly growing aneurysms before they rupture. Modern treatment includes both traditional open surgery and less-invasive endovascular repair using stent grafts.

Most abdominal aortic aneurysms cause no symptoms and are discovered incidentally during imaging done for other reasons or through screening programs. When symptoms do occur, they may include:

• Deep, constant pain in the abdomen or on the side of the abdomen
• Back pain that may radiate to the side or groin
• A pulsing or throbbing sensation near the navel that can be felt when lying down
• In some cases, a tender or enlarged area in the abdomen

If an aneurysm expands rapidly or begins to leak, pain can become severe and sudden. A ruptured aneurysm typically causes abrupt, intense abdominal or back pain, low blood pressure, rapid heart rate, sweating, and signs of shock. This is a surgical emergency.

Because many people have no warning symptoms, screening is especially important for those at higher risk.

An abdominal aortic aneurysm forms when the wall of the aorta weakens and can no longer withstand the pressure of blood flowing through it. The exact reason the wall weakens is not always clear, but several processes contribute:

• Atherosclerosis — The buildup of fat, cholesterol, and other substances on the artery walls is the most common associated factor. It can damage and weaken the aortic wall over time.
• High blood pressure — Chronically elevated pressure places extra stress on the arterial wall.
• Genetic and connective-tissue factors — Some people inherit conditions that affect the strength of blood-vessel walls (for example, Marfan syndrome, Ehlers-Danlos syndrome, or a family history of aneurysms).
• Inflammation or infection — Rarely, infection or inflammatory diseases can weaken the aortic wall.
• Trauma — Severe injury, such as from a motor-vehicle accident, can damage the aorta.

Most aneurysms occur in the segment of the aorta below the kidneys (infrarenal).

Several factors increase the likelihood of developing an abdominal aortic aneurysm:

• Tobacco use — Smoking is the strongest modifiable risk factor. It damages the wall of the aorta and accelerates growth of existing aneurysms. The longer and more heavily a person has smoked, the higher the risk.
• Age — Risk rises significantly after age 65.
• Male sex — Men are much more likely than women to develop abdominal aortic aneurysms.
• Family history — Having a first-degree relative with an aortic aneurysm increases risk.
• High blood pressure and high cholesterol — These contribute to atherosclerosis and wall stress.
• Atherosclerosis in other arteries
• Obesity and sedentary lifestyle

People who have never smoked and have no family history have a substantially lower risk.

The most serious complication is rupture. When an aneurysm bursts, massive internal bleeding occurs. Without immediate surgery, survival is rare. Even with emergency repair, mortality remains high.

Other possible complications include:

• Blood clots that form inside the aneurysm and travel to the legs or other organs, causing blockages
• Infection of the aneurysm wall (rare)
• Compression of nearby structures if the aneurysm becomes very large
• Fistula formation between the aorta and nearby organs (very rare)

Once an aneurysm reaches a certain size or begins to grow quickly, the risk of these complications rises sharply, which is why monitoring and timely repair are essential.

Although not all aneurysms can be prevented, the following measures significantly lower risk and slow growth of existing aneurysms:

• Do not smoke or use any tobacco products. Quitting is the single most important step.
• Control blood pressure and cholesterol through lifestyle and medication if needed.
• Maintain a healthy weight and stay physically active.
• Eat a heart-healthy diet low in saturated fat and rich in fruits, vegetables, and whole grains.
• Follow recommended screening guidelines if you are in a higher-risk group.

If you already have a small aneurysm under observation, strict blood-pressure control and smoking cessation are critical to reduce the chance of growth or rupture.

Many abdominal aortic aneurysms are found when imaging is performed for unrelated reasons. When an aneurysm is suspected or screening is indicated, the primary test is:

• Abdominal ultrasound — A simple, noninvasive, radiation-free test that accurately measures the size of the aorta. It is the preferred screening and monitoring tool.

Additional imaging may include:

• CT angiography or MR angiography to obtain more detailed pictures before planning repair
• Occasional use of conventional angiography in complex cases

Once diagnosed, the size of the aneurysm and its rate of growth determine the management plan. Small aneurysms are usually rechecked with ultrasound every 6–12 months; larger ones are monitored more frequently or referred for repair.

Seek emergency medical care immediately if you experience sudden, severe, or persistent pain in the abdomen or back, especially if the pain is accompanied by dizziness, rapid heartbeat, sweating, or fainting. These can be signs of a rupturing or leaking aneurysm.

Schedule a visit with your healthcare professional if you have risk factors for abdominal aortic aneurysm and have never been screened. Current guidelines generally recommend a one-time ultrasound screening for men ages 65 to 75 who have ever smoked. Screening may also be considered for men in this age group who have never smoked but have a strong family history, and for some women with significant risk factors. Discuss your personal risk with your doctor.

Treatment depends on the size of the aneurysm, how fast it is growing, the presence of symptoms, and the patient’s overall health.

Watchful waiting (medical monitoring)
Small aneurysms (generally less than 5.0–5.5 cm in men or slightly smaller in women) that are not causing symptoms are typically monitored with regular ultrasound. Blood-pressure control, smoking cessation, and statin therapy are recommended.

Repair
Repair is usually recommended when the aneurysm reaches about 5.5 cm in men (or 5.0 cm in women in some guidelines), grows more than 0.5 cm in six months, or causes symptoms. Two main approaches exist:

• Endovascular aneurysm repair (EVAR) — A stent graft is inserted through the arteries in the groin and placed inside the aneurysm. This is less invasive, has a shorter recovery, and is suitable for many patients whose anatomy allows it.
• Open surgical repair — The damaged section of aorta is replaced with a synthetic graft through an abdominal incision. This is a larger operation but may be necessary for certain anatomies or long-term durability in younger patients.

The choice between EVAR and open repair is individualized based on anatomy, age, other medical conditions, and patient preference. Both procedures carry risks, and lifelong imaging follow-up is required after EVAR to monitor the stent graft.

If you have been diagnosed with an abdominal aortic aneurysm under observation:

• Attend every scheduled imaging appointment. Missing follow-up can allow a growing aneurysm to go unnoticed.
• Take blood-pressure and cholesterol medicines exactly as prescribed.
• Stop smoking completely and avoid secondhand smoke.
• Report any new or worsening abdominal or back pain immediately.
• Maintain a healthy lifestyle—regular moderate exercise, balanced diet, and healthy weight—under your doctor’s guidance.

After repair, follow all post-procedure instructions, attend surveillance imaging, and continue aggressive risk-factor management for life.

If you are being evaluated for a possible abdominal aortic aneurysm or have been referred for monitoring or repair, prepare the following information:

• Any symptoms you have noticed, even if mild
• Complete smoking history (when you started, how much, and whether you have quit)
• Family history of aneurysms, sudden death, or connective-tissue disorders
• List of all medicines and supplements
• Results of any previous imaging studies of the abdomen or chest
• Questions about screening, monitoring intervals, lifestyle changes, and the pros and cons of repair options

Bring a family member or friend if possible; the discussion of risks and treatment choices can be detailed.