Abdominal Aortic Aneurysm



  • Focal dilation of the aortic wall with an increase in diameter by at least 50% (>3 cm)
  • 95% are infrarenal
  • Rapid expansion or rupture causes symptoms
  • Rupture can occur into the intraperitoneal or retroperitoneal spaces
  • Intraperitoneal rupture is usually immediately fatal (20% of ruptured AAA)
  • Average growth rate of 0.2–0.5 cm/yr
  • Of ruptures:
    • 90% overall mortality
    • 80% mortality for patients who reach the hospital
    • 50% mortality for patients who undergo emergency repair
  • Of patients who have had endovascular aortic aneurysm repair (EVAR), persistent bloodflow into the aneurysm sac can lead to continued aneurysm growth and rupture

Geriatric Considerations
  • Risk increases with advanced age
  • Present in:
    • 4–8% of all patients older than 65 yr
    • 5–10% of men 65–79 yr old
    • 12.5% of men 75–84 yr old
    • 5.2% of women 75–84 yr old


  • Risk factors are similar to other vascular diseases:
    • Male gender
    • Age >65 yr
    • Family history
    • Cigarette smoking
    • Atherosclerosis
    • HTN
    • Diabetes mellitus
    • Connective tissue disorders:
      • Ehlers–Danlos syndrome
      • Marfan syndrome
  • Uncommon causes:
    • Blunt abdominal trauma
    • Congenital aneurysm
    • Infections of the aorta
    • Mycotic aneurysm secondary to endocarditis
  • Rupture risk factors:
    • Size (annual rupture rates):
      • Aneurysms 5–5.9 cm = 4%
      • Aneurysms 6–6.9 cm = 7%
      • Aneurysms >7 cm = >20%
      • Expansion:
      • A small aneurysm that grows >0.5 cm in 6 mo is at high risk for rupture
    • Gender:
      • For aneurysms 4.0–5.5 cm, women have 4× higher risk of rupture compared to men with similar-sized aneurysms


Signs and Symptoms

  • Abdominal, back, or flank pain:
    • Vague, dull quality
    • Constant, throbbing, or colicky
    • Acute, severe, constant
    • Radiates to chest, thigh, inguinal area, or scrotum
    • Flank pain radiating to the groin in 10% of cases
  • Lower-extremity pain
  • Syncope, near-syncope
  • Unruptured are most often asymptomatic

Physical Exam
  • Unruptured:
    • Abdominal mass or fullness
    • Palpable, nontender, pulsatile mass
    • Intact femoral pulses
  • Ruptured:
    • Classic triad (only 1/3 of the cases):
      • Pain
      • Hypotension
      • Pulsatile abdominal mass
    • Systemic:
      • Hypotension
      • Tachycardia
      • Evidence of systemic embolization
    • Abdomen:
      • Pulsatile, tender abdominal mass
      • Flank ecchymosis (Grey Turner sign) indicates retroperitoneal bleed
      • Only 75% of aneurysms >5 cm are palpable
      • Abdominal tenderness
      • Abdominal bruit
      • GI bleeding
    • Extremities:
      • Diminished or asymmetric pulses in the lower extremities
  • Complications:
    • Large emboli: Acute painful lower extremity
    • Microemboli: Cool, painful, cyanotic toes (“blue toe syndrome”)
    • Aneurysmal thrombosis: Acutely ischemic lower extremity
    • Aortoenteric or aortoduodenal fistula: GI bleeding

Essential Workup

  • Unstable patients:
    • Bedside abdominal US
    • Explorative surgery without further ancillary studies
  • Stable, symptomatic patients:
    • Abdominal CT

Diagnostic Tests and Interpretation

  • Type and cross-match blood
  • CBC
  • Creatinine
  • Urinalysis
  • Coagulation studies

  • Abdominal ultrasound:
    • 100% sensitive and 92–99% specific for detecting AAA prior to rupture
    • Sensitivity has been reported as low as 10% following rupture
    • Ultrasound findings consistent with AAA are enlarged aorta >3 cm or focal dilatation of the aorta
    • Aortic thrombus can lead to the appearance of a normal-caliber aorta. Measuring from outside to outside of the aortic wall can prevent undermeasurement
    • Ultrasound is very limited in the evaluation of patients who have previously had an EVAR, strongly consider CT imaging and expert consultation
  • Abdominal CT scan:
    • Contrast is not necessary to make the diagnosis but CT angiogram is required for surgical planning for an endovascular approach
    • Will demonstrate both aneurysm and site of rupture (intraperitoneal vs. retroperitoneal)
    • Allows more accurate measurement of aortic diameter

Differential Diagnosis

  • Other abdominal arterial aneurysms (i.e., iliac or renal)
  • Aortic dissection
  • Renal colic
  • Biliary colic
  • Musculoskeletal back pain
  • Pancreatitis
  • Cholecystitis
  • Appendicitis
  • Bowel obstruction
  • Perforated viscus
  • Mesenteric ischemia
  • Diverticulitis
  • GI hemorrhage
  • Aortic thromboembolism
  • Myocardial infarction
  • Addisonian crisis
  • Sepsis
  • Spinal cord compression


Pre Hospital

  • Establish 2 large-bore IV lines
  • Rapid transport to the nearest facility with surgical backup
  • Alert ED staff as soon as possible to prepare the following:
    • Operating room
    • Universal donor blood
    • Surgical consultation

Initial Stabilization/Therapy

  • 2 large-bore IV lines
  • Cardiac monitor
  • Hypotensive resuscitation

Ed Treatment/Procedures

For patients suspected of symptomatic AAA:
  • Emergent surgical consult and operative intervention
  • Laparotomy versus endovascular aortic repair (EVAR) by vascular surgeon
  • Diagnostic tests should not delay definitive treatment

Ongoing Care


Admission Criteria
All patients with symptomatic AAA require emergent surgical intervention and admission

Discharge Criteria
Asymptomatic patients only

Follow-Up Recommendations

  • Close vascular surgery follow-up must be arranged prior to discharge
  • Instructions to return immediately for:
    • Any pain in the back, abdomen, flank, or lower extremities
    • Any dizziness or syncope

Pearls and Pitfalls

  • AAA should be on the differential for any patient presenting with pain in the abdomen, back, or flank
  • Symptomatic AAA requires immediate treatment. Do not delay definitive care for extra studies
  • A hemodynamically unstable (i.e., hypotensive) patient should not be taken for CT scan

Additional Reading

  • 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. J Vasc Surg. 2018;67:2–77.
  • Dick F, Erdoes G, Opfermann P, et al. Delayed volume resuscitation during initial management of ruptured abdominal aortic aneurysm. J Vasc Surg. 2013;57(4):943–950.
  • IMPROVE trial investigators. Observations from the IMPROVE trial concerning the clinical care of patients with ruptured abdominal aortic aneurysm. Br J Surg. 2014;101(3):216–224.
  • Kent KC. Abdominal aortic aneurysms. N Engl J Med. 2014;371:2101–2108.

See Also


Adam S. Kaye
Carlo L. Rosen

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