Overview
An abdominal aortic aneurysm (AAA) is a bulge in the lower part of the aorta, the body's largest artery, as it passes through the abdomen. The weakened artery wall balloons outward. If it ruptures, it causes catastrophic internal bleeding that is fatal in most cases without immediate surgery.
How common is it?
Abdominal aortic aneurysms are more common in older men, particularly people who smoke or have smoked. Many cause no symptoms and are detected through screening or a scan for another reason.
Causes and risk factors
An AAA develops when part of the aortic wall weakens and bulges. The exact cause is not fully understood. Smoking, older age, high blood pressure and family history increase risk; cardiovascular disease may coexist.
Common risk factors
- Smoking (the strongest single risk factor)
- Age over 65
- Male sex
- High blood pressure
- Family history of AAA
- High cholesterol
- Other cardiovascular disease
Symptoms
- Most AAAs cause no symptoms until rupture
- A pulsating feeling in the abdomen
- Deep pain in the abdomen, back, or side
- Sudden severe abdominal or back pain may indicate rupture: call your local emergency number immediately
When to see a doctor
Any sudden severe pain in the abdomen or back, especially with feeling faint or collapse, is a medical emergency. Call an ambulance immediately.
Diagnosis
Abdominal ultrasound is the standard screening and diagnostic test. CT scanning gives precise measurements and anatomy before surgery. In the UK, all men are offered a free NHS screening ultrasound at age 65.
Treatments
Surveillance (watchful waiting)
Small AAAs are often monitored with repeat ultrasound. Scan frequency depends on size and local guidance. Surgery may be considered for a large aneurysm, rapid growth or symptoms, not diameter alone.
Endovascular repair (EVAR)
A graft is inserted via the groin arteries to reinforce the aneurysm wall from the inside. Less invasive than open surgery with faster recovery.
Open surgical repair
The damaged aortic section is replaced with a synthetic graft under general anaesthetic. More extensive but may be more durable in younger patients.
Self-care and lifestyle
- Stopping smoking is the single most important step to slow aneurysm growth
- Control blood pressure with medication and a low-salt diet
- Regular gentle exercise improves cardiovascular health without stressing the aorta
- Attend all surveillance appointments as aneurysm growth can be unpredictable
Prevention
Not smoking significantly reduces AAA risk. Regular blood pressure checks and treatment, statin therapy for high cholesterol, and attending NHS screening if eligible can all reduce harm.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to frequency, causes, treatment, key facts, symptoms. This update covers the named sections; a full review of the remaining guide is pending.