Abdominal aortic aneurysm: Difference between revisions

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==Background==
==Background==
*Infrarenal diameter >3cm or >50% increase in size of diameter
*Focal dilation of the abdominal aorta to >50% of normal diameter (typically >3 cm)
*Rupture Risk
*Most commonly infrarenal (95%)
**<4cm: low risk for rupture
*'''Ruptured AAA is a surgical emergency''' with overall mortality of '''65-85%''' (including prehospital deaths)
**4-5cm: 5 year risk 3-12%
*For those who reach OR, mortality is still 40-50%
**>5cm: 25-41%
*Risk factors:
**Rupture possible at any size, most commonly >5cm
**Age > 65 years, male sex (6:1 ratio), smoking (strongest modifiable risk)
**[[Hypertension]], family history, [[COPD]], peripheral vascular disease
**Connective tissue disorders (Marfan, Ehlers-Danlos)
*Risk of rupture increases with size:
**<5 cm: ~1%/year
**5-6 cm: ~10%/year
**>7 cm: ~30%/year


===Risk Factors===
==Clinical Features==
*Smoking
===Classic Triad of Ruptured AAA===
**Risk factor most strongly assoc with AAA
*Abdominal/back pain + hypotension + pulsatile abdominal mass
**Also promotes the rate of aneurysm growth
*Present in only ~50% of cases
*Age (prevalence is negligible in age <50yrs)
*Family history
*HTN


==Clinical Features==
===Presentations===
*Classic triad is pain + hypotension + pulsatile mass
*Intact (unruptured) AAA: usually asymptomatic or incidental finding
**Pain often described as sudden, severe, radiating to back
*Symptomatic unruptured: abdominal/back/flank pain (expanding aneurysm)
*Syncope (10%)
*Ruptured AAA:
*Signs of [[Retroperitoneal hemorrhage]]
**Sudden, severe abdominal or back pain (may radiate to groin, flank, or thigh)
*Massive GI bleed from erosion into intestines
**Hypotension / hemorrhagic [[shock]]
*Pain + AAA = rupture until proven otherwise
**Pulsatile abdominal mass (difficult to palpate in obese or hypotensive patients)
*Acute abdomen + hypotension = possible rupture
**May present as syncope or [[cardiac arrest]]
*Gross [[Hematuria]] can be caused by an aortocaval fistula (very rare)
*Contained rupture: retroperitoneal hemorrhage may be temporarily tamponaded
**Transient hemodynamic stability — '''do not be falsely reassured'''
*Mimics many conditions: [[renal colic]], [[diverticulitis]], [[MI]], musculoskeletal back pain


==Differential Diagnosis==
==Differential Diagnosis==
{{Abdominal Pain DDX Diffuse}}
{{Abdominal Pain DDX Diffuse}}


{{Lower back pain DDX}}
==Evaluation==
 
===Bedside Ultrasound (First-Line in ED)===
==Diagnosis==
*POCUS is the single most important test for unstable patients
[[File:AAA.png|thumb|AAA]]
*'''Sensitivity ~100%''' for detecting aneurysm >3 cm<ref>Tayal VS, et al. Emergency department sonographic measurement of aortic diameter. ''J Ultrasound Med''. 2003;22(12):1291-1294. PMID 14680900</ref>
*Measure outer wall to outer wall in transverse view
*Cannot reliably detect rupture (free fluid may suggest it but absence does not exclude)
*US identifies the aneurysm; CT identifies the rupture


*[[Ultrasound: AAA|Ultrasound]]
===CT Angiography===
**~100% sensitive for increased diameter
*Gold standard for defining anatomy and surgical planning
**Cannot reliably visualize rupture
*Identifies rupture, contained leak, extent, relation to renal arteries
*ONLY for hemodynamically STABLE patients
*Sensitivity for rupture approaches 100%


*CT
===Labs===
**~100% sensitive for incr diameter and rupture
*Type and crossmatch (at least 6 units PRBCs)
**IV contrast is preferred but not essential
*CBC, BMP, coagulation studies, lactate
*'''Do NOT delay resuscitation or imaging for labs'''


==Management==
==Management==
===Rupture===
===Ruptured AAA===
*Do not waste time in ED trying to "stabilize" patient
*Activate massive transfusion protocol
*Immediate surgery consultation/ go to OR
*Permissive hypotension: target SBP 70-90 mmHg
*Crossmatch 6 units of pRBC
*Avoid aggressive crystalloid resuscitation; use blood products
*Pain control (avoid hypotension)
*Emergent vascular surgery consultation
*Antihypertensives (use with caution, goal SBP 110-120 mmHg or MAP 70-80)<ref>Reed, K. Aortic Emergencies, EB Medicine. 2006.</ref>
*'''Unstable patients go directly to OR''' (do NOT delay for CT)
**[[Labetalol]]: 20 mg IV, then 40-80 mg IV q10 min (max 300mg)
**EVAR if anatomy suitable and resources available
**[[Esmolol]]: Bolus 500 mcg/kg, then 50-200 mcg/kg/min
**Open surgical repair if EVAR not feasible
**[[Nitroprusside]]: 0.3 - 0.5 mcg/kg/min, titrate to max 10 mcg/kg/min
*If arrest: consider REBOA or ED thoracotomy with aortic cross-clamp
*Controversial
**Too little (ischemia), too much (increased bleeding)
***Consider allowing for permissive hypotension (SBP 80-100) in conscious patient
**[[Pressors]]
***[[Norepi]] 0.05mcg/kg/min IV; titrate by 0.02mcg/kg/min q5min
***[[Phenylephrine]] 100-180mcg/min; titrate by 25mcg/min q10min
***[[Dopamine]] 5mcg/kg/min; titrate by 5mcg/kg/min q10min


===Asymptomatic===
===Symptomatic Unruptured AAA===
*Prompt vascular surgery outpatient follow-up appt
*Urgent vascular surgery consultation
*Screening frequency:
*Blood pressure control: target SBP 100-120 mmHg
**3-4 cm diameter: 12 months
*Admit for expedited repair
**4-5 cm diameter: 6 months
**5-6 cm diameter: 1 month
*Elective Surgery indicated if:
**AAA > 5.5 cm in men
**AAA > 5 cm in women
**increase in size > 1 cm/year
**increase in size > 5 mm/6 months


==Complications==
===Incidental Asymptomatic AAA===
*[[Aortoenteric fistula]]
*<4 cm: surveillance US every 12 months
*[[Aortocaval fistula]]
*4-5.4 cm: surveillance US every 6 months; vascular referral
*[[Inflammatory abdominal aortic aneurysm]]
*>=5.5 cm: refer for elective repair
*[[Acute limb ischemia]] - embolism to lower extremities
*USPSTF: one-time screening US for men 65-75 who have ever smoked


==Disposition==
==Disposition==
*Admit to OR in cases of ruptured OR
*Ruptured: emergent OR / ICU
*Vasc surg follow up in asymptomatic cases
*Symptomatic unruptured: monitored bed, urgent vascular consult
*Asymptomatic incidental: outpatient vascular referral
 
==See Also==
*[[Aortic dissection]]
*[[Abdominal pain]]
*[[Shock]]
*[[Ultrasound: Aorta]]


==References==
==References==
<references/>
<references/>
*Chaikof EL, et al. SVS practice guidelines for AAA. ''J Vasc Surg''. 2018;67(1):2-77. PMID 29268916
*Kent KC. Abdominal aortic aneurysms. ''N Engl J Med''. 2014;371(22):2101-2108. PMID 25427112


[[Category:Cardiology]]
[[Category:Vascular]]
[[Category:Vascular]]

Latest revision as of 20:56, 8 April 2026

Background

  • Focal dilation of the abdominal aorta to >50% of normal diameter (typically >3 cm)
  • Most commonly infrarenal (95%)
  • Ruptured AAA is a surgical emergency with overall mortality of 65-85% (including prehospital deaths)
  • For those who reach OR, mortality is still 40-50%
  • Risk factors:
    • Age > 65 years, male sex (6:1 ratio), smoking (strongest modifiable risk)
    • Hypertension, family history, COPD, peripheral vascular disease
    • Connective tissue disorders (Marfan, Ehlers-Danlos)
  • Risk of rupture increases with size:
    • <5 cm: ~1%/year
    • 5-6 cm: ~10%/year
    • >7 cm: ~30%/year

Clinical Features

Classic Triad of Ruptured AAA

  • Abdominal/back pain + hypotension + pulsatile abdominal mass
  • Present in only ~50% of cases

Presentations

  • Intact (unruptured) AAA: usually asymptomatic or incidental finding
  • Symptomatic unruptured: abdominal/back/flank pain (expanding aneurysm)
  • Ruptured AAA:
    • Sudden, severe abdominal or back pain (may radiate to groin, flank, or thigh)
    • Hypotension / hemorrhagic shock
    • Pulsatile abdominal mass (difficult to palpate in obese or hypotensive patients)
    • May present as syncope or cardiac arrest
  • Contained rupture: retroperitoneal hemorrhage may be temporarily tamponaded
    • Transient hemodynamic stability — do not be falsely reassured
  • Mimics many conditions: renal colic, diverticulitis, MI, musculoskeletal back pain

Differential Diagnosis

Diffuse Abdominal pain

Evaluation

Bedside Ultrasound (First-Line in ED)

  • POCUS is the single most important test for unstable patients
  • Sensitivity ~100% for detecting aneurysm >3 cm[1]
  • Measure outer wall to outer wall in transverse view
  • Cannot reliably detect rupture (free fluid may suggest it but absence does not exclude)
  • US identifies the aneurysm; CT identifies the rupture

CT Angiography

  • Gold standard for defining anatomy and surgical planning
  • Identifies rupture, contained leak, extent, relation to renal arteries
  • ONLY for hemodynamically STABLE patients
  • Sensitivity for rupture approaches 100%

Labs

  • Type and crossmatch (at least 6 units PRBCs)
  • CBC, BMP, coagulation studies, lactate
  • Do NOT delay resuscitation or imaging for labs

Management

Ruptured AAA

  • Activate massive transfusion protocol
  • Permissive hypotension: target SBP 70-90 mmHg
  • Avoid aggressive crystalloid resuscitation; use blood products
  • Emergent vascular surgery consultation
  • Unstable patients go directly to OR (do NOT delay for CT)
    • EVAR if anatomy suitable and resources available
    • Open surgical repair if EVAR not feasible
  • If arrest: consider REBOA or ED thoracotomy with aortic cross-clamp

Symptomatic Unruptured AAA

  • Urgent vascular surgery consultation
  • Blood pressure control: target SBP 100-120 mmHg
  • Admit for expedited repair

Incidental Asymptomatic AAA

  • <4 cm: surveillance US every 12 months
  • 4-5.4 cm: surveillance US every 6 months; vascular referral
  • >=5.5 cm: refer for elective repair
  • USPSTF: one-time screening US for men 65-75 who have ever smoked

Disposition

  • Ruptured: emergent OR / ICU
  • Symptomatic unruptured: monitored bed, urgent vascular consult
  • Asymptomatic incidental: outpatient vascular referral

See Also

References

  1. ↑ Tayal VS, et al. Emergency department sonographic measurement of aortic diameter. J Ultrasound Med. 2003;22(12):1291-1294. PMID 14680900
  • Chaikof EL, et al. SVS practice guidelines for AAA. J Vasc Surg. 2018;67(1):2-77. PMID 29268916
  • Kent KC. Abdominal aortic aneurysms. N Engl J Med. 2014;371(22):2101-2108. PMID 25427112
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