Abdominal aortic aneurysm: Difference between revisions

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==Background==
==Background==
[[File:Aorta segments.jpg|thumb|Aortic sebments.]]
*Focal dilation of the abdominal aorta to >50% of normal diameter (typically >3 cm)
[[File:Aorta branches.jpg|thumb|Branches of the aorta.]]
*Most commonly infrarenal (95%)
[[File:AneurysmAortaWithArrows.jpg|thumb|CT reconstruction image of an abdominal aortic aneurysm (white arrows).]]
*'''Ruptured AAA is a surgical emergency''' with overall mortality of '''65-85%''' (including prehospital deaths)
*Different types
*For those who reach OR, mortality is still 40-50%
**Fusiform (~92%)- Bulging or ballooning of all sides of the aorta
*Risk factors:
**Saccular (~5%)- Bulging or ballooning of only one side of the aorta
**Age > 65 years, male sex (6:1 ratio), smoking (strongest modifiable risk)
**Mycotic (less than 3%)- Caused by an infection of the vessel wall
**[[Hypertension]], family history, [[COPD]], peripheral vascular disease
***More common in Asian countries, can be as much as 13%
**Connective tissue disorders (Marfan, Ehlers-Danlos)
***May be bacterial, viral, or fungal
*Risk of rupture increases with size:
***May be a complication of infectious endocarditis
**<5 cm: ~1%/year
***Increased risk of rupture
**5-6 cm: ~10%/year
*Infrarenal diameter >3cm or >50% increase in size of diameter
**>7 cm: ~30%/year
**85% of cases are infrarenal <ref name="NJM"></ref>
**Mean growth rate is about 0.2-0.3 cm/yr
*Rupture Risk
**<4cm: low risk for rupture
**4-5cm: 5 year risk 3-12%
**>5cm: 25-41%
**Rupture possible at any size, most commonly >5cm
**Mortality with rupture: 85-90% <ref name="NJM">Kent, K. Abdominal Aortic Aneurysms. The New England Journal of Medicine. 2014; 371:2101-8. DOI: 10.1056/NEJMcp1401430 </ref>


===Risk Factors===
==Clinical Features==
*Gender (male to female ratio 4:1)
===Classic Triad of Ruptured AAA===
*Smoking
*Abdominal/back pain + hypotension + pulsatile abdominal mass
**Risk factor most strongly associated with AAA
*Present in only ~50% of cases
**Also promotes the rate of aneurysm growth
**Direct relationship between risk and number of smoking years
*Age (prevalence is negligible in age <50yrs)
*Family history
*Hypertension
*Hyperlipidemia
*Fluoroquinolone use <ref>P. Wendling for Medscape.  FDA Warns of Aortic Aneurysm Risk with Fluoroquinolones.  https://www.medscape.com/viewarticle/906867.  Accessed 12/26/2018.</ref>


==Clinical Features==
===Presentations===
*Classic triad (only 50% of cases) is [[abdominal pain|pain]] + [[hypotension]] + pulsatile mass
*Intact (unruptured) AAA: usually asymptomatic or incidental finding
**Pain often described as sudden, severe, radiating to back, ripping quality
*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 [[aortoenteric fistula]]
**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
*Unruptured aneurysms are frequently asymptomatic
**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==
==Evaluation==
[[File:AAA.png|thumb|AAA]]
===Bedside Ultrasound (First-Line in ED)===
[[File:AAA_with_Thrombus.gif|thumbnail|Ultrasound of AAA with Thrombus (click to view).<ref>http://www.thepocusatlas.com/aorta-1/</ref>]]
*POCUS is the single most important test for unstable patients
[[File:AneursymCTMark.png|thumb|Abdominal aortic aneurysm seen on CT with a small area of remaining blood flow (white).]]
*'''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>
[[File:Sagital aaa.jpg|thumb|Sagital reconstruction of aortic aneurysm]]
*Measure outer wall to outer wall in transverse view
*'''Labs'''
*Cannot reliably detect rupture (free fluid may suggest it but absence does not exclude)
**Coagulation studies
*US identifies the aneurysm; CT identifies the rupture
**Creatinine
**Urinalysis
**CBC
**Type and cross-match blood


===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%


*'''Imaging'''
===Labs===
**[[Aortic ultrasound|Ultrasound]]
*Type and crossmatch (at least 6 units PRBCs)
***~99% sensitive/98% specific for increased diameter<ref>Rubano E, Mehta N, Caputo W, Paladino L, Sinert R. Systematic review: emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm. Acad Emerg Med. 2013;20(2):128-138. doi:10.1111/acem.12080 </ref>
*CBC, BMP, coagulation studies, lactate
***Cannot reliably visualize rupture (only 4% sensitive)<ref>Rubano E, Mehta N, Caputo W, Paladino L, Sinert R. Systematic review: emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm. Acad Emerg Med. 2013;20(2):128-138. doi:10.1111/acem.12080 </ref>
*'''Do NOT delay resuscitation or imaging for labs'''
**CT
***~100% sensitive for increased diameter and rupture
***IV contrast is preferred but not essential


==Management==
==Management==
===Rupture===
===Ruptured AAA===
[[File:RupturedAAA.png|thumb|Ruptured AAA with an open arrow marking the aneurysm and the closed arrow marking the free blood in the abdomen.]]
*Activate massive transfusion protocol
*Do not waste time in ED trying to "stabilize" patient
*Permissive hypotension: target SBP 70-90 mmHg
*Immediate surgery consultation/ go to OR
*Avoid aggressive crystalloid resuscitation; use blood products
*Crossmatch 6 units of pRBC
*Emergent vascular surgery consultation
*Pain control (avoid hypotension)
*'''Unstable patients go directly to OR''' (do NOT delay for CT)
*Antihypertensives (use with caution, goal SBP 110-120 mmHg or MAP 70-80)<ref>Reed, K. Aortic Emergencies, EB Medicine. 2006.</ref>
**EVAR if anatomy suitable and resources available
**[[Labetalol]]: 20mg IV, then 40-80mg IV q10 min (max 300mg)
**Open surgical repair if EVAR not feasible
**[[Esmolol]]: Bolus 500 mcg/kg, then 50-200 mcg/kg/min
*If arrest: consider REBOA or ED thoracotomy with aortic cross-clamp
**[[Nitroprusside]]: 0.3 - 0.5 mcg/kg/min, titrate to max 10 mcg/kg/min
*Controversial
**Too little (ischemia), too much (increased bleeding)
***Consider allowing for permissive hypotension (SBP 70-90) in conscious patient<ref>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(1):2-77.e2. doi:10.1016/j.jvs.2017.10.044</ref>
**[[Pressors]]
***[[Norepinephrine]] 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===
*Aneurysm > 5 cm: Prompt (within days) vascular surgery outpatient follow-up appt
**Endovascular (75%) vs open repair
*Aneurysm 3-5 cm: Can likely follow up with PCP/surgeon on non-urgent basis
*Screening frequency:
**3-4 cm diameter: 12 months
**4-5 cm diameter: 6 months
**5-6 cm diameter: 1 month
*Elective Surgery indicated if:
**AAA > 5.5 cm in men <ref name="NJM"></ref>
**AAA > 5 cm in women <ref name="NJM"></ref>
**increase in size > 1 cm/year
**increase in size > 5 mm/6 months
 
==Complications==
*[[Aortoenteric fistula]]
*[[Aortocaval fistula]]
*[[Inflammatory abdominal aortic aneurysm]]
*[[Acute limb ischemia]] - embolism to lower extremities
*Graft infection
*Endoleak


===Symptomatic Unruptured AAA===
*Urgent vascular surgery consultation
*Blood pressure control: target SBP 100-120 mmHg
*Admit for expedited repair


==Medication Dosing==
===Incidental Asymptomatic AAA===
<div style="display:none">
*<4 cm: surveillance US every 12 months
{{MedicationDose
*4-5.4 cm: surveillance US every 6 months; vascular referral
| drug = Labetalol
*>=5.5 cm: refer for elective repair
| dose = 20mg IV, then 40-80mg q10min (max 300mg)
*USPSTF: one-time screening US for men 65-75 who have ever smoked
| route = IV
| context = Blood pressure control
| indication = Abdominal aortic aneurysm
| population = Adult
}}
{{MedicationDose
| drug = Esmolol
| dose = 500mcg/kg bolus, then 50-200mcg/kg/min
| route = IV
| context = Blood pressure control; easily titratable
| indication = Abdominal aortic aneurysm
| population = Adult
}}
{{MedicationDose
| drug = Nitroprusside
| dose = 0.3-0.5mcg/kg/min (max 10mcg/kg/min)
| route = IV
| context = Vasodilator for BP control after beta-blockade
| indication = Abdominal aortic aneurysm
| population = Adult
}}
</div>


==Disposition==
==Disposition==
*Admit to OR for ruptured or symptomatic AAA
*Ruptured: emergent OR / ICU
*May discharge asymptomatic cases with close vascular surgery follow up
*Symptomatic unruptured: monitored bed, urgent vascular consult
**Instruct to return immediately if symptoms manifest (abdominal/back pain, syncope, dizziness, extremity pain)
*Asymptomatic incidental: outpatient vascular referral


==External Links==
==See Also==
* [https://rebelem.com/rebel-core-cast-49-0-abdominal-aortic-aneurysm-aaa/ REBEL EM - Abdominal Aortic Aneurysm (AAA)]
*[[Aortic dissection]]
* [http://www.emdocs.net/the-crashing-abdominal-aortic-aneurysm-patient/  emDocs - The Crashing Abdominal Aortic Aneurysm Patient]
*[[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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