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
- 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
- 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:
- Male gender
- Age >65 yr
- Family history
- Cigarette smoking
- 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 6.9–7 cm = 20%
- A small aneurysm that grows >0.5 cm in 6 mo is at high risk for rupture.
- For aneurysms 4.0–5.5 cm, women have 4× higher risk of rupture compared to men with similar sized aneurysms.
- 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
- Abdominal mass or fullness
- Palpable, nontender, pulsatile mass
- Intact femoral pulses
- Classic triad (only 1/3 of the cases):
- Pulsatile abdominal mass
- Evidence of systemic embolization
- 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
- Diminished or asymmetric pulses in the lower extremities
- Large emboli: Acute painful lower extremity
- Microemboli: Cool, painful, cyanotic toes (“blue toe syndrome”)
- Aneurysmal thrombosis: Acutely ischemic lower extremity
- Aortoenteric fistula: GI bleeding
- Unstable patients:
- Bedside abdominal US
- Explorative surgery without further ancillary studies
- Stable, symptomatic patients:
Diagnostic Tests and Interpretation
- Type and cross-match blood
- Coagulation studies
- Plain radiographs:
- Abdominal or lateral lumbar radiographs
- Only if other tests are unavailable
- Curvilinear calcification of the aortic wall or a paravertebral soft-tissue mass indicates abdominal aortic aneurysm (AAA) in 75% of patients.
- Cannot identify rupture
- Negative study does not rule out AAA.
- Abdominal ultrasound:
- 100% sensitive and 92–99% specific for detecting AAA prior to rupture
- In emergent setting, useful to determine presence of AAA.
- Ultrasound findings consistent with AAA are enlarged aorta >3 cm or focal dilatation of the aorta.
- Sensitivity has been reported as low as 10% following rupture.
- Indicated in the unstable patient
- 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
- Other abdominal arterial aneurysms (i.e., iliac or renal)
- Aortic dissection
- Renal colic
- Biliary colic
- Musculoskeletal back pain
- Bowel obstruction
- Perforated viscus
- Mesenteric ischemia
- GI hemorrhage
- Aortic thromboembolism
- Myocardial infarction
- Addisonian crisis
- Spinal cord compression
- 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
For patients suspected of symptomatic AAA:
- 2 large-bore IV lines
- Crystalloid infusion
- Cardiac monitor
- Early blood transfusion
- Avoid over aggressive fluid resuscitation; this leads to increased bleeding
- Emergent surgical consult and operative intervention
- Laparotomy versus endovascular aortic repair (EVAR) by vascular surgeon
- Diagnostic tests should not delay definitive treatment.
All patients with symptomatic AAA require emergent surgical intervention and admission.
Asymptomatic patients only
- 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.
- Bentz S, Jones J. Accuracy of emergency department ultrasound in detecting abdominal aortic aneurysm. Emerg Med J. 2006;23(10):803–804. [PMID:16988313]
- Choke E, Vijaynagar B, Thompson J, et al. Changing epidemiology of abdominal aortic aneurysms in England and Wales: Older and more benign? Circulation. 2012;125(13):1617–1625. [PMID:22361325]
- Lederle FA, Freischlag JA, Tassos C, et al. Long-term comparison of endovascular and open repair of abdominal aortic aneurysm. N Engl J Med. 2012;367:1988–1997. [PMID:23171095]
- Rogers RL, McCormack R. Aortic disasters. Emerg Med Clin N Am. 2004;22:887–908.
- Tibbles C, Barkin A. The aorta. In: Cosby K, Kendall J. Practical Guide to Emergency Ultrasound. Philadelphia, PA: Lippincott Williams & Wilkins; 2006:219–236.
- Aortic Dissection
- Peripheral Artery Disease
- 441.3 Abdominal aneurysm, ruptured
- 441.4 Abdominal aneurysm without mention of rupture
- Abdominal aortic aneurysm, ruptured
- Abdominal aortic aneurysm, without rupture
- 233985008 Abdominal aortic aneurysm (disorder)
- 14336007 Ruptured abdominal aortic aneurysm
Daniel J. Henning
Jason C. Imperato
Carlo L. Rosen
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Abdominal Aortic Aneurysm
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