Abdominal Aortic Aneurysm: Symptoms, Causes & Treatment Guide

What Is an Abdominal Aortic Aneurysm?

An abdominal aortic aneurysm (AAA) is a permanent, localized dilation of the aorta in the abdominal region, typically defined as a diameter greater than 3 cm or 1.5 times the normal diameter. The aorta is the body's largest blood vessel, carrying oxygen-rich blood from the heart to the rest of the body.

The aorta runs from the heart through the chest (thoracic aorta) and into the abdomen (abdominal aorta), where it branches into smaller arteries supplying blood to the legs and pelvic organs. An aneurysm occurs when the arterial wall weakens and begins to bulge outward, similar to a weak spot on an inflated balloon. While aneurysms can develop anywhere along the aorta, the most common location is in the abdominal section, specifically below the level where the arteries to the kidneys branch off.

The normal diameter of the abdominal aorta is approximately 2 cm in most adults. When this diameter exceeds 3 cm, it is classified as an aneurysm. The condition typically develops gradually over many years, with most aneurysms growing at a rate of 1-5 millimeters per year. However, larger aneurysms tend to expand more rapidly, and the risk of rupture increases significantly as the aneurysm grows.

Understanding the anatomy helps explain why AAA is so dangerous. The aortic wall consists of three layers: the intima (inner lining), the media (muscular middle layer), and the adventitia (outer layer). In an aneurysm, the media becomes weakened, often due to degradation of elastic fibers and collagen. This structural weakening allows the artery to expand, and once this process begins, the increasing wall tension accelerates further expansion according to the law of Laplace, which states that wall tension is proportional to the radius of the vessel.

Types of Aortic Aneurysms

Aortic aneurysms are classified by their location and shape. Abdominal aortic aneurysms are the most common type, accounting for approximately 75% of all aortic aneurysms. Thoracic aortic aneurysms occur in the chest portion of the aorta, while thoracoabdominal aneurysms extend through both the chest and abdomen.

Based on shape, aneurysms are classified as fusiform (involving the entire circumference of the aorta, creating a symmetrical bulge) or saccular (involving only a portion of the circumference, creating an asymmetrical outpouching). Fusiform aneurysms are more common in the abdominal aorta, while saccular aneurysms are often associated with trauma, infection, or localized atherosclerotic disease.

What Are the Symptoms of an Abdominal Aortic Aneurysm?

Most abdominal aortic aneurysms cause no symptoms and are discovered incidentally during medical examinations or imaging studies for other conditions. When symptoms do occur, they may include a pulsating sensation near the navel, persistent abdominal or back pain, or a feeling of fullness after eating small amounts.

The asymptomatic nature of AAA is what makes it particularly dangerous. Many people live for years with an aneurysm without knowing it exists. The aneurysm may be detected during a physical examination when a doctor feels a pulsating mass in the abdomen, or it may be discovered incidentally during ultrasound, CT scan, or MRI performed for unrelated reasons such as evaluating kidney problems, back pain, or digestive issues.

When an intact (unruptured) aneurysm does cause symptoms, these may include:

• Pulsating sensation in the abdomen: Some people notice a pulsating or throbbing feeling near the navel, especially when lying down
• Deep, constant abdominal pain: Pain may be felt in the center of the abdomen or slightly to one side
• Back pain: Persistent pain in the lower back that doesn't respond to typical treatments
• Early satiety: Feeling full quickly after eating small amounts of food, due to the aneurysm pressing on the stomach or intestines

It's important to understand that these symptoms are often vague and can easily be attributed to other, more common conditions. This is why screening programs are so valuable - they can detect aneurysms before symptoms develop or before the aneurysm reaches a dangerous size.

Warning Signs of a Ruptured Aneurysm

A ruptured abdominal aortic aneurysm is a life-threatening emergency. The mortality rate for ruptured AAA is extremely high, with approximately 80-90% of patients dying before reaching the hospital or during emergency surgery. Recognizing the warning signs and seeking immediate emergency care is critical.

A ruptured AAA occurs when the weakened arterial wall gives way, allowing blood to escape into the abdominal cavity or retroperitoneal space. The blood loss can be massive and rapid, leading to hemorrhagic shock within minutes. The classic triad of symptoms for ruptured AAA includes sudden onset of severe abdominal or back pain, hypotension (low blood pressure), and a pulsatile abdominal mass - though this complete triad is only present in about 50% of cases.

Symptoms That May Indicate Rapid Growth

If an aneurysm is growing unusually quickly, you may experience new or worsening symptoms even before rupture. These warning signs suggest the aneurysm may be at higher risk and warrant prompt medical evaluation:

• New onset of abdominal or back pain, especially if persistent
• Pain or tenderness when pressing on the abdomen
• A noticeably more prominent pulsation in the abdomen
• Unexplained weight loss or loss of appetite

If you have a known aneurysm and experience any new symptoms, contact your healthcare provider promptly for evaluation. Changes in symptoms may indicate that the aneurysm is expanding or that complications are developing.

What Causes an Abdominal Aortic Aneurysm?

Abdominal aortic aneurysms develop when the wall of the aorta weakens and loses its ability to withstand normal blood pressure. The primary causes include atherosclerosis (hardening of the arteries), genetic factors affecting connective tissue, inflammation, and long-term exposure to risk factors such as smoking and high blood pressure.

The exact mechanism of AAA development is complex and involves multiple interacting factors. At its core, the condition results from an imbalance between the forces that maintain arterial wall integrity and those that promote degradation. Understanding these mechanisms helps explain why certain individuals are at higher risk and how lifestyle modifications can reduce that risk.

Atherosclerosis has long been considered a primary contributor to AAA development. In this process, fatty deposits (plaques) accumulate in the arterial wall, triggering chronic inflammation. The inflammatory response leads to the release of enzymes called matrix metalloproteinases (MMPs) that break down the structural proteins (elastin and collagen) in the arterial wall. This degradation weakens the wall and allows it to stretch under the force of blood pressure.

Genetic factors play a significant role in AAA susceptibility. Studies show that having a first-degree relative (parent, sibling, or child) with AAA increases your risk by 2 to 4 times. Researchers have identified several genes associated with AAA, many of which are involved in maintaining the structure and function of the arterial wall. Additionally, genetic connective tissue disorders such as Marfan syndrome and Ehlers-Danlos syndrome significantly increase the risk of aortic aneurysms at younger ages.

Chronic inflammation in the arterial wall contributes to aneurysm formation and progression. This inflammation can be triggered by various factors, including smoking, infection, and autoimmune conditions. The inflammatory process activates immune cells that release destructive enzymes and signaling molecules, further weakening the arterial wall.

Primary Risk Factors

The Critical Role of Smoking

Smoking deserves special emphasis as it is the strongest modifiable risk factor for AAA. The association between smoking and AAA is stronger than for any other cardiovascular disease. Current smokers have a 4 to 5 times higher risk of developing AAA compared to never-smokers, and even former smokers remain at elevated risk for many years after quitting.

Smoking damages the arterial wall through multiple mechanisms. The toxic chemicals in cigarette smoke promote inflammation, increase oxidative stress, accelerate atherosclerosis, and directly damage the elastic fibers in the arterial wall. Smoking also raises blood pressure and increases heart rate, adding mechanical stress to already weakened arteries.

The good news is that quitting smoking at any age reduces the risk of AAA development and slows the growth of existing aneurysms. Studies show that the rate of aneurysm expansion decreases significantly in those who quit smoking compared to those who continue. This makes smoking cessation one of the most important interventions for anyone at risk of or diagnosed with AAA.

How Is an Abdominal Aortic Aneurysm Diagnosed?

Abdominal aortic aneurysm is most commonly diagnosed through abdominal ultrasound, a painless, non-invasive imaging test that can accurately measure the diameter of the aorta. CT angiography provides more detailed images for surgical planning, while MRI may be used as an alternative without radiation exposure.

Because most AAAs cause no symptoms, diagnosis often occurs through one of three routes: routine screening in high-risk populations, incidental discovery during imaging for other conditions, or emergency evaluation when rupture is suspected. Each diagnostic approach plays an important role in managing this potentially life-threatening condition.

Screening with Ultrasound

Ultrasound is the primary screening tool for AAA because it is accurate, safe, painless, and relatively inexpensive. The examination typically takes 10-15 minutes and involves placing a transducer on the abdomen to create images of the aorta using sound waves. Ultrasound can reliably detect aneurysms and measure their diameter with high accuracy.

International guidelines recommend one-time screening for specific populations:

• All men aged 65-75 who have ever smoked: This is the highest-risk group and benefits most from screening
• All men aged 65 and older: Many countries offer screening to all men in this age group, regardless of smoking history
• Men aged 55-65 with a family history of AAA: Earlier screening is recommended when a first-degree relative has had AAA
• Women aged 65 and older with smoking history or family history: While AAA is less common in women, those with risk factors should consider screening

Large population-based trials have demonstrated that screening programs reduce AAA-related mortality by 40-50% in screened men. This significant benefit has led many countries to implement national screening programs, typically offering a one-time ultrasound to men at age 65.

CT Angiography for Detailed Evaluation

When an aneurysm is detected and surgery is being considered, CT angiography (CTA) provides detailed three-dimensional images of the aorta and surrounding structures. This imaging technique uses contrast dye injected into a vein to visualize the blood vessels in high detail. CTA allows physicians to:

• Precisely measure aneurysm dimensions, including length and diameter
• Assess the anatomy of the aneurysm and surrounding blood vessels
• Evaluate the involvement of branch arteries (renal arteries, iliac arteries)
• Plan the surgical approach and select appropriate graft sizes
• Identify any complications such as blood clots within the aneurysm

Follow-up Monitoring Schedule

Once an aneurysm is detected, regular monitoring is essential to track its growth and determine the optimal timing for intervention. The frequency of follow-up imaging depends on the aneurysm size:

How Is an Abdominal Aortic Aneurysm Treated?

Treatment of abdominal aortic aneurysm depends on the size and growth rate of the aneurysm. Small aneurysms are managed with lifestyle modifications, medication, and regular monitoring. Larger aneurysms (5.5 cm or more in men, 5.0 cm in women) typically require surgical repair, either through open surgery or minimally invasive endovascular repair (EVAR).

The approach to treating AAA is based on balancing the risks of the aneurysm rupturing against the risks of surgical intervention. Because the risk of rupture increases significantly with aneurysm size, treatment recommendations are largely determined by the diameter of the aneurysm, its growth rate, and the patient's overall health status.

Conservative Management for Small Aneurysms

For aneurysms smaller than the surgical threshold, the treatment approach focuses on reducing cardiovascular risk factors, slowing aneurysm growth, and monitoring for changes. This conservative approach is based on evidence showing that the risk of surgery outweighs the benefit for small aneurysms, which have a very low annual rupture risk.

Key components of conservative management include:

• Smoking cessation: The single most important intervention. Quitting smoking can slow aneurysm growth and reduce overall cardiovascular risk
• Blood pressure control: Medications such as beta-blockers, ACE inhibitors, or ARBs help reduce stress on the arterial wall
• Cholesterol management: Statins reduce cardiovascular events and may slow aneurysm progression
• Regular exercise: Moderate physical activity is safe and beneficial; however, heavy lifting and straining should be avoided
• Healthy diet: A heart-healthy diet supports overall cardiovascular health

Surgical Treatment Options

Surgery is typically recommended when the aneurysm reaches 5.5 cm in men or 5.0 cm in women, or when the aneurysm is growing rapidly (more than 1 cm per year). At these sizes, the risk of rupture begins to exceed the risks associated with elective surgery. Two surgical approaches are available:

Open Surgical Repair

Open repair is the traditional surgical approach and has been performed successfully for decades. The procedure involves making an incision in the abdomen, clamping the aorta above and below the aneurysm, removing the diseased portion, and sewing in a synthetic graft (usually made of Dacron or PTFE) to replace the damaged section.

Open surgery is a major procedure requiring general anesthesia and typically involves:

• Hospital stay of 7-10 days
• Recovery period of 3-6 months
• Lower rates of reintervention compared to EVAR
• May be preferred for younger, healthier patients with longer life expectancy

Endovascular Aneurysm Repair (EVAR)

EVAR is a minimally invasive alternative that has become increasingly common since its introduction in the 1990s. The procedure is performed through small incisions in the groin. A stent-graft (a fabric tube supported by a metal framework) is inserted through the femoral artery and guided to the aneurysm using X-ray imaging. Once in position, the stent-graft expands to line the inside of the aneurysm, redirecting blood flow through the graft and excluding the aneurysm from the circulation.

Advantages of EVAR include:

• Smaller incisions and less trauma
• Shorter hospital stay (typically 2-3 days)
• Faster recovery (weeks rather than months)
• Lower perioperative mortality, especially in high-risk patients
• Can be performed under local or regional anesthesia

However, EVAR also has limitations:

• Not all patients have suitable anatomy for EVAR
• Requires lifelong follow-up imaging to detect complications
• Risk of "endoleak" (blood flow around the graft) requiring reintervention
• Higher rates of secondary procedures compared to open repair

Preparing for Surgery

Before surgery, you will undergo comprehensive evaluation including CT angiography for surgical planning, cardiac assessment (ECG, possibly stress testing or echocardiography), blood tests, and lung function tests. Your medical team will optimize any underlying conditions to minimize surgical risk.

Important pre-operative recommendations include:

• Stop smoking: Ideally 8 weeks before surgery, minimum 4 weeks. This significantly improves healing and reduces complications
• Avoid alcohol: Stop drinking alcohol 4 weeks before and after surgery
• Medication review: Some medications may need to be adjusted or stopped
• Physical preparation: Prehabilitation (pre-surgery exercise) may improve outcomes

What Happens After Aneurysm Surgery?

Recovery after AAA surgery depends on the surgical approach. Open surgery requires 7-10 days in hospital and 3-6 months for full recovery. EVAR patients typically go home in 2-3 days and recover within weeks. Both procedures require lifelong follow-up, medication, and lifestyle modifications to prevent complications.

The immediate post-operative period focuses on pain management, preventing complications, and gradually increasing activity. Most patients feel tired for several weeks to months after surgery, especially after open repair. This fatigue is normal and gradually improves with time.

Recovery Timeline

After open surgery, you can expect:

• ICU monitoring for 1-2 days, followed by transfer to a regular ward
• Gradual resumption of eating and drinking over the first few days
• Early mobilization (sitting up, walking short distances) within days
• Suture or staple removal after approximately 2 weeks
• Avoidance of heavy lifting for 6-12 weeks
• Most people return to normal activities within 3-6 months

After EVAR, recovery is faster:

• Usually walking the same day or next day after surgery
• Discharge from hospital within 2-3 days
• Small groin incisions heal within 1-2 weeks
• Most normal activities can resume within 2-4 weeks
• Driving typically allowed after 1-2 weeks (check with your doctor)

Long-term Follow-up

Regardless of the surgical approach, lifelong follow-up is essential. After EVAR, regular imaging (CT or ultrasound) is required to check for endoleaks and ensure the graft remains in position. The typical schedule includes imaging at 1 month, 6 months, and 12 months post-surgery, then annually thereafter. If results are excellent, some centers extend the interval to every 5 years.

After open surgery, less intensive follow-up is usually needed, but annual check-ups are still recommended to monitor for late complications such as graft infection or development of new aneurysms elsewhere in the aorta.

How Can You Prevent an Abdominal Aortic Aneurysm?

Prevention of abdominal aortic aneurysm focuses on modifying controllable risk factors, particularly smoking cessation. Other preventive measures include controlling blood pressure and cholesterol, maintaining a healthy weight, eating a heart-healthy diet, and exercising regularly. People with family history should be screened earlier.

While some risk factors for AAA (such as age, sex, and genetics) cannot be changed, many important risk factors can be modified through lifestyle changes and medical treatment. These same interventions also reduce the risk of other cardiovascular diseases including heart attack and stroke.

Lifestyle Modifications

• Quit smoking: This is the single most important step. Even long-term smokers benefit significantly from quitting. Talk to your doctor about smoking cessation programs, medications, and support resources
• Eat a heart-healthy diet: Emphasize fruits, vegetables, whole grains, lean proteins, and healthy fats. Limit saturated fat, trans fat, sodium, and added sugars
• Maintain a healthy weight: Excess weight, particularly abdominal obesity, increases cardiovascular strain. Even modest weight loss can have significant health benefits
• Exercise regularly: Aim for at least 150 minutes of moderate-intensity aerobic activity per week. Regular exercise improves cardiovascular health and helps control blood pressure and weight
• Limit alcohol: Excessive alcohol consumption can raise blood pressure and contribute to other health problems

Medical Management

Work with your healthcare provider to manage conditions that increase AAA risk:

• Blood pressure control: Target blood pressure of less than 130/80 mmHg in most adults. Medications such as ACE inhibitors and beta-blockers are commonly used
• Cholesterol management: Statins are recommended for most people with or at risk for cardiovascular disease
• Diabetes control: If you have diabetes, work with your doctor to maintain good blood sugar control

What Are the Potential Complications?

The most serious complication of abdominal aortic aneurysm is rupture, which is fatal in approximately 80-90% of cases. Other complications include blood clot formation leading to embolism, compression of nearby structures, and post-surgical complications such as heart attack, kidney problems, or graft infection.

Understanding the potential complications helps emphasize the importance of appropriate monitoring and timely intervention. The risk of complications varies based on the size of the aneurysm, how quickly it is growing, and individual patient factors.

Rupture

Rupture is the most feared complication of AAA. When an aneurysm ruptures, blood escapes from the aorta into the abdominal cavity or retroperitoneal space, causing massive internal bleeding. Without immediate emergency surgery, rupture is uniformly fatal. Even with emergency surgery, mortality rates range from 50-80%, depending on the patient's condition and how quickly surgery can be performed.

The risk of rupture increases with aneurysm size. Approximate annual rupture rates are:

• Less than 4 cm: less than 0.5% per year
• 4.0-4.9 cm: approximately 1% per year
• 5.0-5.9 cm: 3-15% per year
• 6.0-6.9 cm: 10-20% per year
• 7.0 cm or larger: 20-40% per year

Other Cardiovascular Risks

People with AAA are at increased risk of other cardiovascular diseases because they often share common risk factors. Studies show that patients with AAA have significantly higher rates of:

• Heart attack: The same atherosclerosis that contributes to AAA often affects the coronary arteries
• Stroke: Vascular disease can also affect the carotid arteries and cerebral circulation
• Peripheral artery disease: Reduced blood flow to the legs can cause claudication (leg pain with walking)

For this reason, patients with AAA should be treated for overall cardiovascular risk, not just the aneurysm itself. This includes blood pressure control, cholesterol management, and antiplatelet therapy when indicated.