Asynchronous curriculum, AAA:
“There is no disease more conducive to clinical humility than aneurysm of the aorta.” –William Osler
How many AAAs will I diagnose in my career?
How important are risk factors in the diagnosis of AAA?
How do you palpate an aorta?
Can I exclude AAA based on physical exam providing that I do palpate it?
What is the rule of 5’s for AAAs and annual mortality/ sudden death?
What is the disposition for AAA?
First, read this review article1on AAAs (most of it is the bibliography, really).
~1/2000 cases of abdominal pain seen in the ED
~ An average EP seeing 4500 patients per year (2.5 patients/ hour, 36 hours/ week) will see this once every 1-2 years 30%1of the time will initially misdiagnose
~ 50-90 % mortality
Next, examine these graphs to visualize the exponential significance of risk factors:
(There is also benefit to smoking cessation—quitting smoking will cut the risk of rupture in half and also slow the rate of increase in the size of the AAA.7)
How to examine the aorta via abdominal palpation:
Don’t watch this video, just look at the image:
Sensitivity/ Specificity of Physical Exam for AAA
Fink et al2:
- “The examination was conducted with the patient supine with knees raised and the abdomen relaxed…”
- “Both hands were then placed on the abdomen with palms down and an index finger on either side of the pulsating area to measure the aortic width.”
- Take into account skinfold thickness when measuring the width of the pulsation.
- “Auscultation was not performed because bruits were not found to contribute to the diagnosis of AAA.”
JAMA’s Rational Clinical Examination3:
- “each systole should move the 2 fingers apart…”
- “it is often easier, initially, to probe for one side of the aorta at a time…”
- “it is the width, and not the intensity, of the aortic pulsation that determines the diagnosis of AAA… “
- “rarely warranted in persons younger than 50 years because of the low frequency of disease in this group.”
- Abdominal bruits, femoral bruits, and absent femoral pulses—not useful in the diagnosis of AAA
- No reports known of physical exam ever rupturing a AAA
Next, read this abstractby Fink et al2(summary of results in table below).
Sensitivity/ Specificity of Physical Exam for AAA
|Conditions||Number of patients examined||Sensitivity||Specificity|
|Waist < 40”, AAA >= 5.0cm||12||100%||unspecified|
|Obese waist AND aorta palpable||125||82%||59%|
|AAA 3.0-4.0 cm||unspecified||61%||unspecified|
|AAA 4.0-5.0 cm||unspecified||69%||unspecified|
|AAA 5.0cm +||unspecified||82%||unspecified|
Rule of 5’s (for AAAs):4
- At 5cm, 5% risk of rupturing within the year
- 5% of sudden deaths are due to ruptured AAA
Does size matter?
<10% of ruptured AAAs are < 4cm, but once ruptured, they’re equally deadly5. source
“All asymptomatic aortic aneurysms should be referred for follow-up. Abdominal aortic aneurysms ≥5 cm in diameter are at an increased risk of rupture (size is measured from outer wall to outer wall) and require prompt (days) follow-up. Aneurysms of 3 to 5 cm are less likely to rupture and can be followed by their primary care physicians or surgeons. The management of patients with small, asymptomatic aneurysms (including the timing of surgery) varies. Symptomatic aneurysms of any size are considered emergent.”
|Ruptured AAA||STAT OR|
|Symptomatic AAA, any size||Same-day vascular consult|
|Incidental AAA, <5cm||PCP/general surgery followup|
|Incidental AAA, 5 or more cm||Prompt (within a few days) follow-up|
- Assar AN, Zarins CK. Ruptured abdominal aortic aneurysm: a surgical emergency with many clinical presentations. Postgrad Med J. 2009;85(1003):268 LP-273. http://pmj.bmj.com/content/85/1003/268.abstract.
- Fink HA, Lederle FA, Roth CS, Bowles CA, Nelson DB, Haas MA. The accuracy of physical examination to detect abdominal aortic aneurysm. Arch Intern Med. 2000;160(6):833-836. http://www.ncbi.nlm.nih.gov/pubmed/10737283.
- Lederle FA, Simel DL. The rational clinical examination. Does this patient have abdominal aortic aneurysm? . JAMA. 1999;281(1):77-82. http://www.ncbi.nlm.nih.gov/pubmed/9892455.
- Aggarwal S, Qamar A, Sharma V, Sharma A. Abdominal aortic aneurysm: A comprehensive review. Exp Clin Cardiol. 2011;16(1):11-15. http://www.ncbi.nlm.nih.gov/pubmed/21523201.
- Nicholls SC, Gardner JB, Meissner MH, Johansen HK. Rupture in small abdominal aortic aneurysms. J Vasc Surg. 1998;28(5):884-888. http://www.ncbi.nlm.nih.gov/pubmed/9808857.
- Prince LA, Johnson GA. Aneurysmal Disease. In: Tintinalli JE, Stapczynski JS, Ma OJ, Yealy DM, Meckler GD, Cline DM, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e. New York, NY: McGraw-Hill Education; 2016. http://accessmedicine.mhmedical.com/content.aspx?aid=1121496310.
- Howard DPJ, Banerjee A, Fairhead JF, et al. Age-specific incidence, risk factors and outcome of acute abdominal aortic aneurysms in a defined population. Br J Surg. 2015;102(8):907-915. http://www.ncbi.nlm.nih.gov/pubmed/25955556.