Causes
The exact cause of AAA is not fully understood, but it is primarily linked to atherosclerosis, a condition that causes hardening and narrowing of the arteries. Aneurysms develop when the forces of blood flow continually weaken the arterial wall over time.- Atherosclerosis:
- This is the most common underlying cause. It involves the buildup of plaque (fatty deposits, cholesterol, calcium) on the inner lining of arteries, which can weaken the arterial wall and make it prone to bulging.
- Risk Factors for Atherosclerosis (and thus AAA):
- Smoking: The strongest and most significant risk factor. Smoking directly damages the aortic wall and accelerates atherosclerosis.
- Age: AAAs are most common in men over 65. The risk increases with age.
- Gender: Men are about 4-5 times more likely to develop AAAs than women.
- High Blood Pressure (Hypertension): Increases the pressure on the aortic walls, contributing to weakening.
- High Cholesterol (Hyperlipidemia): Contributes to atherosclerosis.
- Family History: Having a close relative (parent, sibling) with an AAA significantly increases your risk. Genetic predisposition plays a strong role.
- Other Aneurysms: If you have an aneurysm in another blood vessel (e.g., popliteal artery), your risk of an AAA is higher.
- Race: More common in Caucasians than in other ethnic groups.
- Rare Causes:
- Genetic Disorders: Conditions that affect connective tissue, such as Marfan syndrome or Ehlers-Danlos syndrome, can cause weaker arterial walls.
- Inflammation of the Aorta (Aortitis): Less common, but inflammation can weaken the wall.
- Infection (Mycotic Aneurysm): An infection that weakens the aortic wall.
- Trauma: Severe injury to the abdomen.
Symptoms
Most small to medium-sized AAAs are asymptomatic, meaning they do not cause any symptoms and are often discovered incidentally during imaging tests for other conditions. Symptoms usually appear when the aneurysm grows large, leaks, or ruptures.- No Symptoms (Most Common for Small/Medium AAAs): This is why screening is important for high-risk individuals.
- Symptoms of a Growing AAA (when present):
- Pulsating Sensation: A deep, constant ache or pulsing sensation in the abdomen, often to the side of the belly button.
- Back Pain: Persistent pain in the lower back, often radiating to the buttock or groin.
- Abdominal Pain: A deep, gnawing pain in the abdomen that does not resolve.
- Symptoms of a Ruptured AAA (Medical Emergency - Life-Threatening):
- Sudden, Severe Abdominal or Back Pain: Often described as tearing or ripping.
- Pain Radiating: To the back, groin, or legs.
- Massive Internal Bleeding: Leading to rapid blood loss.
- Signs of Shock:
- Dizziness or lightheadedness.
- Rapid heart rate.
- Low blood pressure.
- Nausea and vomiting.
- Clammy skin.
- Loss of consciousness.
- Symptoms of a Leaking AAA: Similar to a ruptured AAA but may develop more gradually.
- Symptoms of Clotting Complications: Rarely, a small clot can break off from the aneurysm and travel to the legs or feet, causing:
- Sudden pain, numbness, or coolness in a limb.
- Discoloration (e.g., blueness) of toes or foot.
Diagnosis
AAAs are often found incidentally or through screening for high-risk individuals. Definitive diagnosis and monitoring involve imaging tests.- Physical Exam: A doctor may feel a pulsating mass in the abdomen, especially in thin individuals, but this is not always reliable.
- Screening Ultrasound:
- Recommended for men aged 65-75 who have ever smoked, and for men and women over 60 with a family history of AAA.
- A non-invasive, painless test that uses sound waves to create an image of the aorta and measure its diameter. It's an excellent screening tool.
- CT Scan (Computed Tomography) of the Abdomen:
- The most common and accurate test for diagnosing and monitoring the size of an AAA.
- Provides detailed cross-sectional images of the aorta and surrounding structures. Used for confirmation, precise sizing, and surgical planning.
- Often used with IV contrast (CTA) to visualize blood flow.
- MR Angiography (MRA):
- Similar to CTA, uses MRI with contrast to visualize the aorta and measure the aneurysm size. Used for patients who cannot receive CT contrast or for long-term follow-up.
- Abdominal X-ray: May show calcification in the aortic wall, which suggests an aneurysm, but it's not a definitive diagnostic tool for AAA size.
Treatment
Treatment for AAA depends on the size of the aneurysm, its growth rate, the presence of symptoms, and the patient's overall health. The primary goal is to prevent rupture.- Watchful Waiting (Surveillance) for Small AAAs:
- For small aneurysms (typically less than 5.0-5.5 cm in diameter) that are not causing symptoms, regular monitoring with ultrasound or CT scans (every 6-12 months) is recommended.
- Lifestyle modifications and medication to control risk factors are crucial during this phase.
- Lifestyle Modifications and Risk Factor Management:
- Smoking Cessation: The most important step to prevent aneurysm growth and rupture.
- Blood Pressure Control: Medications (e.g., beta-blockers, ACE inhibitors) to keep blood pressure at target levels to reduce stress on the aortic wall.
- Cholesterol Management: Statins to lower cholesterol and reduce atherosclerosis progression.
- Diabetes Management: Strict control of blood sugar levels.
- Healthy Diet and Regular Exercise: To maintain overall cardiovascular health.
- Surgical Repair (for large, growing, or symptomatic AAAs):
- Typically recommended for aneurysms 5.0-5.5 cm or larger, rapidly growing aneurysms, or any symptomatic aneurysm, due to the high risk of rupture.
- Open Surgical Repair:
- Involves a large incision in the abdomen to directly access and replace the diseased segment of the aorta with a synthetic graft.
- Highly durable but more invasive, with a longer recovery time.
- Endovascular Aneurysm Repair (EVAR):
- A minimally invasive procedure where small incisions are made in the groin, and a stent graft (a fabric tube supported by a metal stent) is delivered through a catheter to the aneurysm site.
- The stent graft expands within the aorta, reinforcing the weakened wall and redirecting blood flow through the graft, preventing blood from entering the aneurysm sac.
- Less invasive, shorter hospital stay, quicker recovery, but requires regular follow-up imaging (e.g., CT scans) to ensure the graft remains in place and is functioning correctly.
- Emergency Surgery: If an AAA ruptures or leaks, immediate emergency surgery (open repair) is required to stop the bleeding, but the mortality rate is very high.
Living With an Aortic Aneurysm Under Surveillance
Most people with an abdominal aortic aneurysm spend years, sometimes the rest of their life, in surveillance rather than surgery. That goes well when scans happen on schedule, the risk factors that drive growth are treated, and the household knows what a rupture looks like.
How often the scan repeats
The interval is set by diameter: a small aneurysm just above the size that defines one is rechecked every few years, one approaching five centimeters is scanned yearly, and one just under the repair threshold is scanned about every six months. Ultrasound is enough for most surveillance; CT is reserved for planning. Rapid growth over a single year, or any new abdominal or back pain, moves the discussion to repair regardless of size. Women's aortas are smaller, so repair is often considered at a slightly smaller diameter. Our aneurysm screening article covers who qualifies for the one-time Medicare ultrasound.
The risk factors that actually change growth
Stopping smoking is the one intervention shown to slow aneurysm growth and lower rupture risk; treating nicotine dependence with varenicline or nicotine replacement is part of aneurysm care, not an afterthought. Blood pressure control with an agent such as lisinopril and a statin such as atorvastatin are prescribed because the same atherosclerosis affects the coronary and leg arteries; coronary artery disease and peripheral arterial disease are looked for even without symptoms.
A medication warning worth knowing
Fluoroquinolone antibiotics such as ciprofloxacin and levofloxacin carry an FDA warning about aortic aneurysm and dissection, and are avoided in people with a known aneurysm unless no alternative exists. Mention the aneurysm whenever an antibiotic is prescribed, including at urgent care.
Exercise, lifting, and daily life
Walking, cycling, swimming, and moderate exercise are encouraged and appear safe; heavy straining such as maximal lifting or breath-holding effort is discouraged because it spikes aortic pressure. Sexual activity, travel, and ordinary work are fine. Tell any surgeon or anesthesiologist about the aneurysm before an unrelated operation. First-degree relatives, especially brothers and sisters over 60, should have a one-time ultrasound, since family history raises risk several-fold.
After repair, and the signs that cannot wait
Endovascular repair needs lifelong imaging because the graft can leak or shift, and a missed follow-up scan is how a repaired aneurysm gets into trouble; open repair needs far less. At any stage, sudden severe abdominal or back pain, fainting, or a cold, painful leg means calling 911 rather than driving to the office. Our cardiovascular team coordinates surveillance with vascular surgery. NHLBI and the U.S. Preventive Services Task Force publish patient guidance on screening and surveillance.
If you have an aneurysm and cannot remember when your last scan was, schedule a visit; keeping the interval is most of the treatment.