Aortic Aneurysm — Causes, Symptoms, Screening & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

An aortic aneurysm is an abnormal, localised dilation of the aorta — the body's largest artery, which carries oxygenated blood from the heart to the rest of the body. Defined as aortic diameter 50% or more above normal (normal aortic diameter is up to 2.0 cm) or more commonly as an absolute diameter of 3 cm or more. The most common location is the infrarenal abdominal aorta (abdominal aortic aneurysm/AAA), followed by the thoracic aorta (thoracic aortic aneurysm/TAA). AAA affects 1-2% of men over 65 and carries a high rupture risk when large. Rupture of an AAA is a surgical emergency with overall mortality of 65-85% — many patients die before reaching hospital. The NHS England AAA Screening Programme invites all men at age 65 for a single abdominal ultrasound.

The most common cause is atherosclerosis (plaque-related weakening and inflammation of the aortic wall, leading to proteolytic matrix degradation and wall dilatation). Other causes include hypertension (high blood pressure weakens arterial walls), hereditary connective tissue disorders (Marfan syndrome — FBN1 mutation; Ehlers-Danlos syndrome — particularly vascular type — significant for thoracic aneurysms), bicuspid aortic valve (associated with TAA through shared genetic aortopathy), aortic dissection, large vessel vasculitis (Takayasu arteritis, giant cell arteritis), and mycotic (infected) aneurysm — rare but dangerous. Major risk factors for AAA: male sex (6:1 ratio vs. women); age over 65; smoking (4-8x increased risk — the most important modifiable risk factor); hypertension; family history (first-degree relative with AAA increases risk 2-3x); dyslipidaemia; and peripheral arterial disease.

Most aortic aneurysms are asymptomatic and discovered incidentally on imaging performed for another reason, or on AAA screening. When symptomatic, AAA causes a pulsatile abdominal mass (felt above the umbilicus), dull aching back or flank pain (from aneurysm expansion), and occasionally tender pulsatile mass. TAA may cause chest or back pain, hoarseness (left recurrent laryngeal nerve compression), cough, stridor, or dysphagia from compression of adjacent structures. Rupture is a catastrophic emergency presenting with the classic triad: sudden severe tearing or ripping pain in the abdomen, back, or flank; hypotension and haemodynamic shock; pulsatile abdominal mass. Leaking or contained rupture may present with intermittent or less severe pain and temporary haemodynamic stability — deceptive and easily missed. Any suspected rupture demands immediate emergency assessment — do not perform CT before surgical team is alerted.

Abdominal ultrasound is the first-line diagnostic test — accurate, non-invasive, inexpensive, no radiation, used for population screening. AAA is defined as aortic diameter of 3 cm or more (anteroposterior outer-to-outer wall measurement). Surveillance intervals by size: 3.0-4.4 cm — annual ultrasound; 4.5-5.4 cm — 3-monthly ultrasound; 5.5 cm or more — refer to vascular surgery for intervention. CT angiography provides detailed anatomy essential for surgical planning — confirms size, morphology (fusiform vs. saccular), relationship to renal and iliac arteries, and EVAR suitability. MRI angiography when CT is contraindicated (renal failure, contrast allergy). The UK NHS AAA Screening Programme invites all men aged 65 for abdominal ultrasound — a single screen is sufficient as aneurysms rarely develop de novo after a negative screen at 65. Women aged 65+ with risk factors (family history, smoking) may also be screened in some centres. For TAA: CT angiography of the thoracic aorta is standard.

Treatment depends on aneurysm size and rate of expansion. Small AAAs (below 5.5 cm in men, below 5.0 cm in women): regular ultrasound surveillance per NICE intervals; optimise modifiable risk factors: blood pressure control (target below 130/80 mmHg — ACE inhibitors, ARBs, calcium channel blockers); statin therapy (atorvastatin 80 mg — reduces cardiovascular mortality and may slow AAA progression); smoking cessation (most effective single intervention for slowing aneurysm growth). Avoid heavy lifting and Valsalva manoeuvres. Large AAAs (5.5 cm or more in men, 5.0 cm or more in women) or rapidly expanding (more than 1 cm/year) or symptomatic: elective surgical repair. Endovascular aneurysm repair (EVAR): minimally invasive — stent-graft deployed through femoral arteries under fluoroscopic guidance; lower 30-day mortality vs. open repair; requires lifelong surveillance (CT at 1 month, 12 months, then annually — watching for endoleak). Open surgical repair (OSR): aortic aneurysm replaced with prosthetic Dacron graft via laparotomy — higher operative risk but excellent long-term durability without ongoing surveillance imaging. EVAR vs. OSR decision based on anatomical suitability, patient fitness, and shared decision-making. Ruptured AAA: emergency OSR or EVAR (if anatomy suitable) — mortality remains 40-50% even with treatment; immediate transfer to vascular surgical centre.

Rupture is the most feared complication of aortic aneurysm — abdominal aortic aneurysm rupture carries an overall mortality of 65–85%, with many patients dying before reaching hospital. Rapid expansion (more than 1 cm/year) significantly increases rupture risk. Aortic dissection — a tear in the inner wall of the aorta — can occur independently or in association with aneurysm, causing acute severe back or chest pain and potentially fatal organ ischaemia. Distal thromboembolism from mural thrombus within the aneurysm sac can occlude peripheral arteries, causing acute limb ischaemia or renal infarction. Post-EVAR complications include endoleak (persistent blood flow into the aneurysm sac — Types I and III are high-risk and require reintervention), stent migration, graft limb occlusion, and post-implantation syndrome.

Smoking cessation is the single most important modifiable risk factor — smokers have 4-8x increased AAA risk, and smoking is the only lifestyle factor proven to accelerate aneurysm expansion. Optimal blood pressure control (target below 130/80 mmHg) — ACE inhibitors and beta-blockers may slow aortic dilatation in Marfan syndrome (bisoprolol + losartan NICE-recommended). Statin therapy for cardiovascular risk reduction and potential plaque stabilisation. Maintain healthy weight; exercise regularly (evidence suggests aerobic exercise is safe even with small aneurysms — specific guidance for patients with large aneurysms). Screen: all men at age 65 (NHS AAA Screening Programme); women with risk factors should discuss opportunistic screening with their GP. For patients with Marfan syndrome or BAV: annual aortic root MRI from adolescence; elective repair at lower thresholds (4.5-5.0 cm for Marfan; 5.0-5.5 cm for BAV) to reduce dissection and rupture risk.

Call emergency services (999/911) immediately for: sudden severe tearing or ripping pain in the abdomen, back, or flank in anyone with a known aortic aneurysm or with risk factors (male over 65, smoker, hypertensive) — this is suspected AAA rupture, a life-threatening emergency; collapse, dizziness, or loss of consciousness alongside abdominal or back pain; severe abdominal pain of sudden onset in any older adult with cardiovascular risk factors — consider ruptured aneurysm even without a known diagnosis. If you have a known aneurysm: attend all surveillance appointments without exception; contact your GP or vascular surgery team urgently if you develop new or worsening back pain, abdominal discomfort, or pulsatile abdominal sensation — even if symptoms are mild. Do not drive yourself to hospital with severe pain — call 999.