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Abdominal aortic aneurysm

Last updated: May 27, 2021

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Abdominal aortic aneurysm (AAA) is a focal dilatation of the abdominal aorta to more than 1.5 times its normal diameter. AAAs are classified by location as either suprarenal or infrarenal aneurysms. Men of advanced age are at increased risk for their formation; smoking and hypertension are also major risk factors. AAAs are frequently asymptomatic and therefore detected incidentally. Symptomatic AAAs can manifest with lower back pain, a pulsatile abdominal mass, and a bruit on auscultation. Abdominal ultrasound is the best initial and confirmatory test to diagnose AAAs and determine their extent. Observation, close follow-up, and reduction of cardiovascular risk factors are indicated for small aneurysms, whereas pronounced (> 5.5 cm) or rapidly expanding aneurysms require surgery. Surgical treatment involves open resection of the aneurysm with graft placement or, increasingly, endovascular stent placement. The prognosis is markedly worse if dissection or aneurysm rupture occurs. AAA rupture typically presents with sudden onset of severe tearing back or abdominal pain, a painful pulsatile mass, and hypovolemic shock, and should be managed with emergent surgery. All men between 65 and 75 years of age with a history of smoking should be screened once with an ultrasound to exclude an AAA. See also thoracic aortic aneurysm for more information.

  • Localized dilation of all three layers of the abdominal aortic wall (intima, media, and adventitia) to ≥ 3 cm [1]

  • Peak incidence: 60–70 years (rare in patients < 50 years)
  • Sex: > : ∼ 2:1

Epidemiological data refers to the US, unless otherwise specified.


Aortic aneurysms are usually asymptomatic or have nonspecific symptoms. They are often discovered incidentally on ultrasound or CT scan. Rupture or dissection of the aneurysm is a life-threatening condition (see “Ruptured AAA”).

The diagnosis of AAA is confirmed by imaging showing aortic diameter > 3 cm. Unstable patients should be taken directly to the OR for emergency surgery if ruptured AAA is suspected (see ruptured AAA). There are no laboratory findings specific to AAA. [1]

Imaging should not delay treatment if AAA is suspected in hemodynamically unstable patients.

Imaging [6][7]

  • Duplex ultrasound
    • Indications
      • Best initial and confirmatory test in:
        • Asymptomatic patients
        • Patients with abdominal pain and no known AAA or risk factors for AAA
      • To determine the presence, size, and extent of an aneurysm
      • Screening and surveillance
    • Supportive findings
      • Dilatation of the aorta ≥ 3 cm [1]
      • Thrombus may be present (hyperechoic)
    • Disadvantages: Abdominal ultrasound has low sensitivity for aneurysmal leaks, branch artery involvement, and suprarenal involvement, and its findings are insufficient for procedural planning. [1][8]

If a large (> 5.5 cm) aneurysm is seen on ultrasound in a patient presenting with abdominal pain, refer the patient for treatment immediately.

  • CT angiography abdomen and pelvis with IV contrast
    • Indications
      • Imaging modality of choice in symptomatic patients and for preintervention planning
      • To help confirm the diagnosis when ultrasound is not possible in asymptomatic patients
      • More detailed evaluation of the location, size, and extent of the aneurysm, involvement of branch vessels, and presence of thrombus or rupture
    • Supportive findings
      • Dilatation of the aorta ≥ 3 cm and possibly branch vessels [1]
      • Thrombus may also be present (hypodense, nonenhancing)

  • MR angiography abdomen and pelvis with and without IV contrast
  • Arteriography (aortography abdomen)
    • Indications
      • To help confirm diagnosis or for preintervention planning if the patient has significant contraindications to CTA and MRA
      • More detailed assessment of the aortic lumen
    • Supportive findings: contrast column in the lumen of the aneurysm and branch vessels [6]
    • Disadvantage: may mask the actual diameter of the aneurysm (because a mural thrombus does not appear on arteriography)
Abdominal vs. thoracic aortic aneurysm
Characteristics Abdominal aortic aneurysm Thoracic aortic aneurysm


  • Advanced age
  • Predominantly men
  • More common than TAA
  • Advanced age
  • Predominantly men
Clinical features
  • Feeling of pressure in the chest
  • Thoracic back pain

The differential diagnoses listed here are not exhaustive.

Approach [1]

  • Unstable patients (e.g., in case of rupture): emergency repair within 90 minutes (see “Ruptured AAA”)
  • Symptomatic patients with impending rupture or leaking AAA; : urgent aneurysm repair within hours Consider optimizing conditions for a successful outcome: If this delays surgery for a few hours, the patient should be monitored in an ICU in the meantime.
  • Asymptomatic patients: elective aneurysm repair or aneurysm surveillance
  • All patients: reduction of cardiovascular risk factors [1]

Invasive treatment: AAA repair

Procedures [1]

The long-term survival and complication rates of endovascular and open surgical repair are similar, and these procedures each have their advantages and disadvantages.

  • Endovascular aneurysm repair (EVAR)
    • Indications: minimally invasive procedure that is preferred over open surgical repair for most aneurysms, especially in patients with a high operative risk
    • Procedure: Under fluoroscopic guidance, an expandable stent graft is placed via the femoral or iliac arteries intraluminally at the site of the aneurysm.
    • Disadvantage: Reintervention rates are higher for EVAR than for OSR.
  • Open surgical repair (OSR)
    • Indications
    • Procedure: A laparotomy is performed and the dilated segment of the aorta is replaced with a tube graft or Y-prosthesis (bifurcated synthetic stent graft).

Preoperative assessment for elective repair [1]

  • Calculation of mortality risk: used to weigh operative risk against life expectancy for patients being considered for elective AAA repair
Elective AAA repair postoperative mortality risk score [10]
Parameter Points
Planned intervention EVAR 0
OSR (infrarenal) 2
OSR (suprarenal) 4
Aneurysm size (mm) < 65 0
≥ 65 2
Age ≤ 75 years 0
> 75 years 1
Sex Male 0
Female 1
Comorbidities History of MI or cerebrovascular disease 1
Serum creatinine (mg/dL) < 1.5 0
≥ 1.5 2


  • 0–4 points: low risk
  • 5–7 points: medium risk
  • 8–10 points: high risk
  • 11–14 points: prohibitively high risk

  • Preoperative management of comorbid conditions
  • Additional considerations: Life expectancy should also be considered when planning elective repair. [11]

Perioperative care for AAA repair

Surveillance after repair [1][7]

Postoperative surveillance following EVAR is important because it can help to detect possible endoleaks, sac growth, device migration, and device failure. Because of the risk of an anastomotic aneurysm or aneurysmal dilation in the visceral aorta or iliac arteries, regular follow-up is recommended after OSR.

  • CT angiography abdomen and pelvis with IV contrast
    • After 1 month, 12 months, then annually
    • After 6 months if an abnormality is seen on the 1-month scan
  • MR angiography abdomen and pelvis without and with IV contrast
    • Indication: contraindications to CT angiography, avoidance of radiation
    • Artifacts might be visible depending on stent material and orientation.
  • Duplex ultrasound
    • Indication: may be used for annual follow-up if the 12-month scan is unremarkable
    • Abdominal and pelvic CT angiography with IV contrast should still be performed every 5 years.

Conservative treatment: AAA surveillance without repair

  • Small (< 5.5 cm), asymptomatic AAA can typically be observed with interval surveillance ultrasound. [12]
    • To identify the expansion rate and thus decrease the risk of rupture
    • Frequency depends on the size of the aneurysm.
Follow-up frequency for AAA surveillance [1]
Maximum diameter of the abdominal aorta Recommended follow-up interval
2.5–2.9 cm
3–3.9 cm
4–4.9 cm
5.0–5.4 cm

Regular monitoring is essential because aneurysm size and expansion rate are strong predictors for the risk of rupture.

We list the most important complications. The selection is not exhaustive.

Unstable patients should be taken to the OR immediately for emergency surgery if ruptured AAA is suspected.

Ruptured abdominal aortic aneurysm

Symptomatic abdominal aortic aneurysm

Primary prevention [1]

See “ASCVD prevention” for detailed information on primary prevention.

  • The following measures are thought to reduce the risk of developing an AAA:
    • Eating nuts, fruits, and vegetables more than three times a week
    • Exercising more than once a week
    • Smoking cessation

Secondary prevention [1][15]

  • Screening for abdominal aneurysm with abdominal ultrasound
    • One-time screening in men aged 65–75 years with a history of smoking [1][15]
    • Also consider one-time screening for the following groups: [1][15]
      • Individuals aged 65–75 years with a positive family history
      • Individuals aged > 75 years in good health with a positive family history
      • Women aged 65–75 years with a history of smoking
      • Individuals aged > 75 years in good health with a history of smoking
    • Consider rescreening after 10 years if the aortic diameter was > 2.5 cm but < 3 cm in the initial assessment. [1]

Tertiary prevention [1]

  • Elective repair to prevent rupture (see “Treatment”)
  • Aneurysm surveillance
  • Smoking cessation
  1. Graciaa DS, Mosunjac MB, Workowski KA, Kempker RR. Asymptomatic Cardiovascular Syphilis With Aortic Regurgitation Requiring Surgical Repair in an HIV-Infected Patient. Open Forum Infect Dis. 2017; 4 (4). doi: 10.1093/ofid/ofx198 . | Open in Read by QxMD
  2. Chaikof EL, Dalman RL, Eskandari MK, et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. Journal of Vascular Surgery. 2018; 67 (1): p.2-77.e2. doi: 10.1016/j.jvs.2017.10.044 . | Open in Read by QxMD
  3. Reis SP et al.. ACR Appropriateness Criteria ® Pulsatile Abdominal Mass Suspected Abdominal Aortic Aneurysm. J Am Coll Radiol. 2017; 14 (5): p.S258-S265. doi: 10.1016/j.jacr.2017.01.027 . | Open in Read by QxMD
  4. Francois CJ et al.. ACR Appropriateness Criteria ® Abdominal Aortic Aneurysm: Interventional Planning and Follow-Up. J Am Coll Radiol. 2018; 15 (5): p.S2-S12. doi: 10.1016/j.jacr.2018.03.008 . | Open in Read by QxMD
  5. AIUM. AIUM Practice Guideline for the Performance of Diagnostic and Screening Ultrasound Examinations of the Abdominal Aorta in Adults. J Ultrasound Med. 2015; 34 (8): p.1-6. doi: 10.7863/ultra. . | Open in Read by QxMD
  6. Dent B, Kendall RJ, Boyle AA, Atkinson PR. Emergency ultrasound of the abdominal aorta by UK emergency physicians: a prospective cohort study. Emerg Med J. 2007; 24 (8): p.547-549. doi: 10.1136/emj.2007.048405 . | Open in Read by QxMD
  7. Eslami MH et al.. Comparison of a Vascular Study Group of New England risk prediction model with established risk prediction models of in-hospital mortality after elective abdominal aortic aneurysm repair. J Vasc Surg. 2015; 62 (5): p.1125-1133.e2. doi: 10.1016/j.jvs.2015.06.051 . | Open in Read by QxMD
  8. Paraskevas KI, Eckstein H-H, Schermerhorn ML. Guideline Recommendations for the Management of Abdominal Aortic Aneurysms. Angiology. 2019; 70 (8): p.688-689. doi: 10.1177/0003319719825518 . | Open in Read by QxMD
  9. Filardo G et al.. Surgery for small asymptomatic abdominal aortic aneurysms. Cochrane Database Syst Rev. 2015 . doi: 10.1002/14651858.cd001835.pub4 . | Open in Read by QxMD
  10. Maleux G, Koolen M, Heye S. Complications after endovascular aneurysm repair. Semin Intervent Radiol. 2009; 26 (1): p.3-9. doi: 10.1055/s-0029-1208377 . | Open in Read by QxMD
  11. Owens DK et al.. Screening for Abdominal Aortic Aneurysm. JAMA. 2019; 322 (22): p.2211. doi: 10.1001/jama.2019.18928 . | Open in Read by QxMD
  12. Rahimi SA. Abdominal Aortic Aneurysm. In: Rowe VL, Abdominal Aortic Aneurysm. New York, NY: WebMD. Updated: December 19, 2016. Accessed: February 6, 2017.
  13. Kumar V, Abbas AK, Aster JC. Robbins & Cotran Pathologic Basis of Disease. Elsevier Saunders ; 2014
  14. Thompson MM. Infrarenal abdominal aortic aneurysms. Curr Treat Options Cardiovasc Med. 2003; 5 (2): p.137-146. doi: 10.1007/s11936-003-0022-z . | Open in Read by QxMD
  15. Wang LJ, Prabhakar AM, Kwolek CJ. Current status of the treatment of infrarenal abdominal aortic aneurysms. Cardiovasc Diagn Ther. 2018; 8 (S1): p.S191-S199. doi: 10.21037/cdt.2017.10.01 . | Open in Read by QxMD
  16. Moreno DH, Cacione DG, Baptista-Silva JC. Controlled hypotension versus normotensive resuscitation strategy for people with ruptured abdominal aortic aneurysm. Cochrane Database of Systematic Reviews. 2018 . doi: 10.1002/14651858.cd011664.pub3 . | Open in Read by QxMD
  17. Schwartz SA et al.. CT Findings of Rupture, Impending Rupture, and Contained Rupture of Abdominal Aortic Aneurysms. AJR Am J Roentgenol. 2007; 188 (1): p.W57-W62. doi: 10.2214/ajr.05.1554 . | Open in Read by QxMD
  18. Karow T, Lang-Roth R. Allgemeine und Spezielle Pharmakologie und Toxikologie. Dr. med. Thomas Karow (2012 und 2013) ; 2010
  19. Kliegman RM, Stanton BF, Geme JS, Schor NF, Behrman RE. Nelson Textbook of pediatrics. Elsevier (2011) ; 2011
  20. Agabegi SS, Agabegi ED. Step-Up To Medicine. Lippincott Williams & Wilkins ; 2013
  21. Upchurch GR. Abdominal Aortic Aneurysm. Am Fam Physician. 2006; 73 (7): p.1198-1204.
  22. Brewster DC, Cronenwett JL, Hallett JW Jr, Johnston W, Krupski WC, Matsumura JS. Guidelines for the treatment of abdominal aortic aneurysms. J Vasc Surg. 2003; 37 (5): p.1106-1117. doi: 10.1067/mva.2003.363 . | Open in Read by QxMD
  23. Jang T. Bedside Ultrasonography Evaluation of Abdominal Aortic Aneurysm. In: Taylor CR, Bedside Ultrasonography Evaluation of Abdominal Aortic Aneurysm. New York, NY: WebMD. Updated: September 20, 2015. Accessed: February 6, 2017.