Abdominal aortic aneurysm

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

ruptured abdominal aortic aneurysm (AAA)

1st line – urgent surgical repair

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1st line –

urgent surgical repair

If the patient has a suspected ruptured AAA, get immediate help from a senior colleague and discuss the patient with a regional vascular service to consider transfer for urgent surgical repair if:[42][70]

AAA is confirmed on bedside aortic ultrasound
OR
Bedside aortic ultrasound is not immediately available, or is non-diagnostic but AAA is still suspected.

If the patient has been accepted by a regional vascular service, ensure they leave the referring unit within 30 minutes of the decision to transfer.[42][70]

Specialist input from a regional vascular service should inform the decision to transfer a patient and their suitability for urgent surgical repair.[2][70]

No single symptom, sign, or patient-related risk factor, or patient risk assessment tool (scoring system), should be used to determine whether surgical repair is suitable for a patient.[42]
However, certain patients (such as those who are in cardiac arrest and/or have a persistent loss of consciousness) are unlikely to survive surgical repair.[2][42]

If surgery is deemed appropriate, either endovascular aneurysm repair (EVAR) or open surgical repair may be performed.[2][42]

EVAR is recommended in most patients with ruptured infrarenal AAA.[2][42] It provides greater benefit than open surgical repair in most patients, particularly for men over 70 years and women of any age.[2][42] Benefits of EVAR include lower perioperative mortality, and less time in hospital in general (and critical care in particular).[42][103] However, open surgical repair may provide a better risk/benefit balance for men aged under 70 years.[42] In young patients with suspected connective tissue disorders and an AAA, open surgical repair is recommended as first option.[2]
Local anaesthesia should be considered, if tolerated, for a patient undergoing EVAR.[2][42][113]
Cell salvage or an ultrafiltration device is recommended if large blood loss is anticipated or the risk of disease transmission from banked blood is considered high.[77] Intraoperative cell salvage and re-transfusion should be considered during open AAA repair.[2]
Blood transfusion is recommended if the intraoperative haemoglobin level is <100 g/L in the presence of ongoing blood loss.[77] Consider use of fresh frozen plasma and platelets in a ratio with packed blood cells of 1:1:1.[2][77]

If surgical repair is deemed inappropriate, make treatment and monitoring decisions with the multidisciplinary team as part of an individualised end of life care plan.[121] Involve the patient and/or their carers where possible.[121]

Plus – resuscitation measures

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Plus –

resuscitation measures

Treatment recommended for ALL patients in selected patient group

Initiate immediate resuscitation measures while waiting for transfer to a regional vascular service. These include:

Supplemental oxygen
Intravenous access
Arterial catheter; urinary catheter
Hypotensive resuscitation (permissive hypotension) if the patient is conscious.[2]
- The European Society for Vascular Surgery recommends aiming for a target systolic blood pressure (SBP) of 70-90 mmHg.[2] In practice, this target SBP is a good approach if definitive surgical repair is imminent.
- However, the Royal College of Emergency Medicine recommends a higher target SBP of 90-120 mmHg, which may be used by the emergency department team to ensure adequate perfusion while waiting for input from a regional vascular service.[70]
- If available, use blood and blood products with a suggested ratio of fresh frozen plasma/red blood cells close to 1:1.[2][77]

Plus – perioperative antibiotic therapy

Plus – analgesia

Plus – VTE prophylaxis

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Plus –

VTE prophylaxis

Treatment recommended for ALL patients in selected patient group

Give venous thromboembolism (VTE) prophylaxis to all patients undergoing surgical repair of AAA.[2][77][149] If a patient has a ruptured AAA they are at increased risk of major bleeding but are also at high risk for VTE. Therefore:[2]

Consider using mechanical prophylaxis with intermittent pneumatic compression until the risk of major bleeding has subsided.[2]
Once the risk of major bleeding has subsided (usually within 24-48 hours of surgery unless there are signs of ongoing bleeding or a clinically significant coagulopathy), start pharmacological prophylaxis with either a low molecular weight heparin (LMWH), such as enoxaparin, or unfractionated heparin.[2]
Continue pharmacological prophylaxis throughout the hospital stay, and also after discharge in certain patients based on individual risk factors and level of mobility.[2]

The European Society for Vascular Surgery also recommends to consider intraoperative administration of heparin once the rupture bleeding has been controlled.[2]

Primary options

enoxaparin: consult specialist for guidance on dose

heparin: consult specialist for guidance on dose

Consider – treatment of infectious/inflammatory cause

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Consider –

treatment of infectious/inflammatory cause

Additional treatment recommended for SOME patients in selected patient group

Once the patient is stable and urgent surgical repair for the rupture has been prioritised, infectious or inflammatory aetiology should be addressed.

If the patient has a suspected infectious aneurysm, early diagnosis and prompt treatment is essential to improve outcomes.[2] Open surgical repair has traditionally been considered the preferred option for infectious aneurysms, though more recent data suggest that endovascular aneurysm repair (EVAR) may be associated with equal or superior outcomes.[2][8][174] Extensive debridement is often needed during urgent surgical repair in these patients. There is a high risk of secondary infective complications and further surgery may be needed for new infectious lesions. Intraoperative cultures should be taken to accurately guide subsequent antibiotic therapy; however, empirical antibiotics are often administered, as peripheral blood cultures and surgical specimen cultures are negative in a large proportion of patients.[8] Prolonged antibiotic therapy (from 4-6 weeks duration to lifelong) may be indicated depending on the specific pathogen, the type of operative repair, and the patient’s immunological state.[2][8]

Inflammatory aortitis (caused by, for example, Takayasu arteritis or giant cell arteritis) is treated with high-dose corticosteroids and surgery.[8][102] Tamoxifen has been used alone or in combination with corticosteroids in inflammatory aortitis.[2][175][176] However, the superiority of combined therapy over corticosteroids alone remains unproven.[177]

Surgical treatment of inflammatory AAAs poses a different challenge to surgeons compared with standard degenerative AAAs due to the increased risk of iatrogenic bowel, caval, iliac vein, and ureteral injuries during open surgical repair and the increased inflammatory response to endoprosthesis implantation.[2] Preoperative ureteral stent placement may be required to release hydronephrosis and help identification of the ureter during surgery.[2][175] High-level evidence comparing open repair and EVAR is not available.[175][178] It remains unclear whether EVAR alone has any beneficial effect on hydronephrosis, and retroperitoneal fibrosis seems to resolve at a slower rate compared with open repair.[175]

symptomatic, but not ruptured abdominal aortic aneurysm (AAA)

1st line – urgent surgical repair

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1st line –

urgent surgical repair

Urgently discuss any patient with a symptomatic, unruptured AAA with a regional vascular service.[42][70]

The development of new or worsening pain may herald aneurysm expansion and impending rupture.

Urgent surgical repair is indicated regardless of AAA diameter.[8][42][77][101]

Endovascular aneurysm repair is widely used in the management of patients with symptomatic AAA.[122][123]
Under some circumstances, intervention may be delayed for several hours to optimise conditions to ensure successful repair; these patients should be closely monitored in the ICU with strict management of their blood pressure.[77]
Cell salvage or an ultrafiltration device is recommended if large blood loss is anticipated or the risk of disease transmission from banked blood is considered high.[77] Intraoperative cell salvage and re-transfusion should be considered during open AAA repair.[2]

Blood transfusion is recommended if the intraoperative haemoglobin level is <100 g/L in the presence of ongoing blood loss.[77] Consider use of fresh frozen plasma and platelets in a ratio with packed blood cells of 1:1:1.[2][77]

Plus – perioperative antibiotic therapy

Plus – analgesia

Plus – VTE prophylaxis

Back

Plus –

VTE prophylaxis

Treatment recommended for ALL patients in selected patient group

Give venous thromboembolism (VTE) prophylaxis to all patients undergoing surgical repair of AAA.[77][149]

Consider pharmacological VTE prophylaxis with a low molecular weight heparin (LMWH), such as enoxaparin, for a minimum of 7 days for a patient undergoing endovascular aneurysm repair or open surgical repair if their risk of VTE outweighs their risk of bleeding.[149]
If pharmacological VTE prophylaxis is contraindicated, consider mechanical VTE prophylaxis with either anti-embolism stockings or intermittent pneumatic compression.[149]

Primary options

enoxaparin: consult specialist for guidance on dose

Consider – treatment of infectious/inflammatory cause

Back

Consider –

treatment of infectious/inflammatory cause

Additional treatment recommended for SOME patients in selected patient group

Once the patient is stable and urgent surgical repair for symptomatic AAA has been prioritised, infectious or inflammatory aetiology should be addressed.

If the patient has a suspected infectious aneurysm, early diagnosis, prompt treatment with antibiotics, and urgent surgical repair is essential to improve outcomes.[2] Open surgical repair has traditionally been considered the preferred option for infectious aneurysms, though more recent data suggest that endovascular aneurysm repair (EVAR) may be associated with equal or superior outcomes.[2][8][174] Extensive debridement is often needed during urgent surgical repair in these patients. There is a high risk of secondary infective complications and further surgery may be needed for new infectious lesions. Intraoperative cultures should be taken to accurately guide subsequent antibiotic therapy; however, empirical antibiotics are often administered, as peripheral blood cultures and surgical specimen cultures are negative in a large proportion of patients.[8] Prolonged antibiotic therapy (from 4-6 weeks duration to lifelong) may be indicated depending on the specific pathogen, the type of operative repair, and the patient’s immunological state.[2][8]

ONGOING

incidental finding of asymptomatic abdominal aortic aneurysm (AAA): <5.5 cm (but not >4.0 cm and rapidly growing)

1st line – surveillance

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1st line –

surveillance

For a small (<5.5 cm) AAA detected as an incidental finding, surveillance is preferred to surgical repair until the theoretical risk of rupture exceeds the estimated risk of operative mortality.[2][3][42][103]

However, repair may be considered if the AAA measures >4 cm and is growing rapidly (>1 cm in 1 year).[42] In some countries, repair may be considered for women if their AAA measures ≥5 cm.[2][101][103]
Organise referral to a regional vascular service for any patient with a small (<5.5 cm) asymptomatic AAA (that is detected outside of a screening programme). Following diagnosis, ensure they are seen within 12 weeks.[42]
Bear in mind that the threshold for referral and consideration of surgical repair for an asymptomatic AAA may vary in different countries. Check your local protocol.

Check your local protocol for guidance on frequency of surveillance because this may vary in different countries.[2][8][42]

In the UK, the National Institute for Health and Care Excellence recommends the following intervals for surveillance:[42]
- Annually if the AAA measures 3.0 to 4.4 cm
- Every 3 months if the AAA measures 4.5 to 5.4 cm.

Plus – aggressive cardiovascular risk management

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Plus –

aggressive cardiovascular risk management

Treatment recommended for ALL patients in selected patient group

Offer the patient information, support, and interventions for secondary prevention of cardiovascular disease.[2][42]

Refer all patients to a stop smoking service. This is key because smoking is the most important risk factor for development, expansion, and rupture of AAA.[2] See Smoking cessation.
All patients with AAA should receive antiplatelet therapy unless contraindicated. The European Society of Cardiology (ESC) states that treatment with single antiplatelet agent (aspirin or clopidogrel) may be reasonable.[132] Anticoagulation can be considered in cases of intraluminal thrombus or occlusive aneurysm, in light of the role of the mural thrombus in aneurysmal progression.[132]
The European Society of Cardiology recommends that all patients with symptomatic peripheral vascular disease should also be started on lipid lowering agents if low density lipoprotein (LDL) cholesterol >2.5 mmol/L (>97 mg/dL), and antihypertensives if systolic blood pressure >140 mmHg, unless contraindicated.[133]Aboyans V, Ricco JB, Bartelink MEL, et al. 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the European Society for Vascular Surgery (ESVS): document covering atherosclerotic disease of extracranial carotid and vertebral, mesenteric, renal, upper and lower extremity arteries. Endorsed by: the European Stroke Organization (ESO), the Task Force for the Diagnosis and Treatment of Peripheral Arterial Diseases of the European Society of Cardiology (ESC) and of the European Society for Vascular Surgery (ESVS). Eur Heart J. 2018 Mar 1;39(9):763-816.[134]Visseren FLJ, Mach F, Smulders YM, et al. 2021 ESC Guidelines on cardiovascular disease prevention in clinical practice: developed by the task force for cardiovascular disease prevention in clinical practice with representatives of the European Society of Cardiology and 12 medical societies with the special contribution of the European Association of Preventive Cardiology (EAPC) [in Spanish]. Rev Esp Cardiol (Engl Ed). 2022 May;75(5):429.
Other considerations include:
- Strategies targeted at a healthy lifestyle including weight management, diet, nutrition, and exercise.[42] See Obesity in adults.
- Management of other comorbidities such as diabetes.[42] See Type 2 diabetes in adults.

Consider – treatment of infectious/inflammatory cause

Back

Consider –

treatment of infectious/inflammatory cause

Additional treatment recommended for SOME patients in selected patient group

Infectious or inflammatory aetiology should be addressed.

If the patient has a suspected infectious aneurysm, early diagnosis and prompt treatment with antibiotics and urgent surgical repair is essential to improve outcomes.[2] Open surgical repair has traditionally been considered the preferred option for infectious aneurysms, though more recent data suggest that endovascular aneurysm repair (EVAR) may be associated with equal or superior outcomes.[2][8][174] Extensive debridement is often needed in these patients. There is a high risk of secondary infective complications and further surgery may be needed for new infectious lesions. Intraoperative cultures should be taken to accurately guide subsequent antibiotic therapy; however, empirical antibiotics are often administered, as peripheral blood cultures and surgical specimen cultures are negative in a large proportion of patients.[8] Prolonged antibiotic therapy (from 4-6 weeks duration to lifelong) may be indicated depending on the specific pathogen, the type of operative repair, and the patient’s immunological state.[2][8]

Inflammatory aortitis (caused by, for example, Takayasu's arteritis or giant cell arteritis) is treated with high-dose corticosteroids and surgery.[8][102] Tamoxifen has been used alone or in combination with corticosteroids in inflammatory aortitis.[2][175][176] However, the superiority of combined therapy over corticosteroids alone remains unproven.[177]

incidental finding of asymptomatic abdominal aortic aneurysm (AAA): ≥5.5 cm (or >4.0 cm and rapidly growing)

1st line – elective surgical repair

Back

1st line –

elective surgical repair

In general, surgical repair is indicated for patients with large (≥5.5 cm) asymptomatic AAA.[2][42] Surgery may also be considered if the AAA measures >4 cm and is growing rapidly (>1 cm in 1 year).[42] In some countries, repair may be considered for women if their AAA measures ≥5 cm.[2][101][103]

Organise referral to a regional vascular service for any patient with an asymptomatic AAA. Following diagnosis, ensure they are seen:[42]
- Within 2 weeks if the AAA measures ≥5.5 cm
- Within 12 weeks if the AAA measures 3.0 to 5.4 cm.
Bear in mind that the threshold for referral and consideration of surgical repair for an asymptomatic AAA may vary in different countries.[2][8][42] Check your local protocol.

Discuss the risks and benefits of elective surgical repair versus conservative management (with ultrasound surveillance) with the patient based on their current and expected future health.[42] For AAA detected as an incidental finding, conservative management is preferred to repair until the theoretical risk of rupture exceeds the estimated risk of operative mortality.[2][3][42]

Treatment decisions should be made jointly with the patient and should take into account factors such as:[2][42]
- Aneurysm size and morphology[42]
- The patient’s age, life expectancy, fitness for surgery, and any comorbidities[42]
  - Assessment should include a medical history and clinical examination, functional assessment, full blood count and electrolytes (including assessment of renal function), and ECG. Additional testing, including static echocardiogram, pulmonary function tests, and cardiopulmonary exercise testing, may be considered based on the individual circumstances of the patient.[2][42]
- The risk of AAA rupture if it is not repaired[42]
- The short- and long-term benefits and risks, including disadvantages of repair such as stay in hospital, operation risks, recovery period, potential need for other procedures, and the need for surveillance imaging appointments[42]
- The uncertainties around estimates of risk for AAAs ≥5.5 cm[42]
- In patients with an underlying genetic cause or connective tissue disorder, the threshold diameter for considering repair should be individualised, depending on:[2]
  - Anatomical features
  - Underlying genetics: rupture risk is higher at smaller aortic diameters in some conditions, and surgical repair is more challenging in certain disorders owing to the increased arterial wall fragility and anatomy.[2]
Refer any patient who meets the threshold for surgical repair but is not initially fit for surgery to the appropriate specialist for optimisation of their fitness status and comorbidities, before reconsideration of surgical repair.[2] This may include a patient with:[2]
- Active cardiovascular disease (e.g., unstable angina, decompensated heart failure, severe valvular disease, significant arrhythmia)
- Poor functional capacity (e.g., unable to climb two flights of stairs, walk up a hill, jog for at least 10 minutes, perform heavy housework [scrubbing floor or moving furniture], or mow a lawn)
- Significant clinical risk factors (e.g., pre-existing COPD, recent decline in respiratory function, history of symptomatic cerebrovascular disease, severe renal impairment [eGFR <30 mL/min/1.73 m²]).

Plus – preoperative cardiovascular risk reduction

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Plus –

preoperative cardiovascular risk reduction

Treatment recommended for ALL patients in selected patient group

Offer the patient information, support, and interventions for secondary prevention of cardiovascular disease.[42] Elective repair in asymptomatic patients allows for preoperative assessment, cardiac risk stratification, and medical optimisation of other comorbidities. Addressing modifiable cardiovascular risk factors preoperatively improves long-term survival after AAA repair.[140] Consider the following:

Referral to a stop smoking service.[42] See Smoking cessation.
Strategies targeted at a healthy lifestyle including weight management, diet, nutrition, and exercise.[42] See Obesity in adults.
All patients with AAA should receive antiplatelet therapy unless contraindicated. The European Society of Cardiology (ESC) states that treatment with single antiplatelet agent (aspirin or clopidogrel) may be reasonable.[132] Anticoagulation can be considered in cases of intraluminal thrombus or occlusive aneurysm, in light of the role of the mural thrombus in aneurysmal progression.[132]
Optimisation of their medication.[42]
- Continue antiplatelet monotherapy with aspirin or a P2Y ₁₂ inhibitor (e.g., clopidogrel), if the patient is already taking this, during the perioperative period after open and endovascular AAA repair.[2]
- Avoid continuing dual antiplatelet therapy in most patients due to the risk of serious bleeding.[2] However, continuation may be considered in certain high-risk patients, including those undergoing interventional coronary revascularisation before AAA repair because they are at risk of in-stent thrombosis.[2]
- Discontinue anticoagulation prior to surgery for at least:[2]
  - 5 days for warfarin
  - 2 days for direct oral anticoagulants (DOACs).
- Do not start a beta-blocker prior to AAA repair.[2][42] However, continue a beta-blocker if a patient is already taking this at an appropriate dose.[2]
Lipid modification.[42]
- Start a statin at least 4 weeks before elective AAA surgery, if possible, to reduce cardiovascular morbidity and mortality; continue indefinitely.[2][60][141][142] See Hypercholesterolaemia and Hypertriglyceridaemia.
- Perioperative statin use reduces cardiovascular events during non-cardiac surgery.[143]
Management of diabetes.[42] See Type 2 diabetes in adults.
Management of hypertension.[42] See Essential hypertension.

Plus – perioperative antibiotic therapy

Plus – analgesia

Plus – VTE prophylaxis

Consider – treatment of infectious/inflammatory cause

Back

Consider –

treatment of infectious/inflammatory cause

Additional treatment recommended for SOME patients in selected patient group

Infectious or inflammatory aetiology should be addressed.

Use of this content is subject to our disclaimer

Abdominal aortic aneurysm

ruptured abdominal aortic aneurysm (AAA)

urgent surgical repair

resuscitation measures

perioperative antibiotic therapy

analgesia

VTE prophylaxis

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

treatment of infectious/inflammatory cause

symptomatic, but not ruptured abdominal aortic aneurysm (AAA)

urgent surgical repair

perioperative antibiotic therapy

analgesia

VTE prophylaxis

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

treatment of infectious/inflammatory cause

incidental finding of asymptomatic abdominal aortic aneurysm (AAA): <5.5 cm (but not >4.0 cm and rapidly growing)

surveillance

aggressive cardiovascular risk management

treatment of infectious/inflammatory cause

incidental finding of asymptomatic abdominal aortic aneurysm (AAA): ≥5.5 cm (or >4.0 cm and rapidly growing)

elective surgical repair

preoperative cardiovascular risk reduction

perioperative antibiotic therapy

analgesia

VTE prophylaxis

Primary options

treatment of infectious/inflammatory cause

Abdominal aortic aneurysm

Treatment algorithm

ruptured abdominal aortic aneurysm (AAA)

urgent surgical repair

resuscitation measures

perioperative antibiotic therapy

analgesia

VTE prophylaxis

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

treatment of infectious/inflammatory cause

symptomatic, but not ruptured abdominal aortic aneurysm (AAA)

urgent surgical repair

perioperative antibiotic therapy

analgesia

VTE prophylaxis

Primary options

These drug options and doses relate to a patient with no comorbidities.

Primary options

Drug choice, dose and interactions may be affected by the patient's comorbidities. Check your local drug formulary.

Primary options

treatment of infectious/inflammatory cause

incidental finding of asymptomatic abdominal aortic aneurysm (AAA): <5.5 cm (but not >4.0 cm and rapidly growing)

surveillance

aggressive cardiovascular risk management

treatment of infectious/inflammatory cause

incidental finding of asymptomatic abdominal aortic aneurysm (AAA): ≥5.5 cm (or >4.0 cm and rapidly growing)

elective surgical repair

preoperative cardiovascular risk reduction

perioperative antibiotic therapy

analgesia

VTE prophylaxis

Primary options

treatment of infectious/inflammatory cause