Abdominal aortic aneurysm
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In health care, an abdominal aortic aneurysm is "an abnormal balloon- or sac-like dilatation in the wall of the abdominal aorta which gives rise to the visceral, the parietal, and the terminal (iliac) branches below the aortic hiatus at the diaphragm."
Various methods of diagnostic imaging can be used to measure the diameter of the aorta.
A clinical practice guideline by the U.S. Preventive Services Task Force (USPSTF) 'recommends one-time screening for abdominal aortic aneurysm (AAA) by ultrasonography in men age 65 to 75 years who have ever smoked'. This is a grade B recommendation. An re-analysis of the meta-analysis estimated a number needed to screen of approximately 850 patients.
- Screening men ages 65-74 years (not restricted to ever smokers). 'Men in whom abdominal aortic aneurysms (> or =3 cm in diameter) were detected were followed-up... Patients with an aortic diameter of 3·0–4·4 cm were rescanned at yearly intervals, whereas those with an aortic diameter of 4·5–5·4 cm were rescanned at 3-monthly intervals ... Surgery was considered on specific criteria (diameter > or =5.5 cm, expansion > or =1 cm per year, symptoms)'.
This trial reported significant short ( number needed to screen after 4 years of approximately 590 to prevent nonfatal ruptured AAA plus AAA-related deaths) and long term ( number needed to screen after 7 years of approximately 280 to prevent nonfatal ruptured AAA plus AAA-related deaths) benefit and cost effectiveness. Subsequent randomized controlled trials also found benefit:
- number needed to screen after 4 years of 300
- number needed to screen after and after 7 years of 563 (calculation).
More recently, a clinical prediction rule may help identify patients for screening.
MEDICARE criteria for screening
Effective January 1, 2007, provisions of the SAAAVE Act (Screening Abdominal Aortic Aneurysm Very Efficiently) now provide a free, one-time, ultrasound AAA screening benefit for those qualified seniors. Men who have smoked at least 100 cigarettes during their life, and men and women with a family history of AAA qualify for the one-time ultrasound screening.
Enrollees must visit their healthcare professional for their Welcome to Medicare physical within six months of enrollment in order to qualify for the free screening.
The Welcome to Medicare Physical Exam must be completed within the first six months of Medicare eligibility, but there is no published time limit thereafter for completion of the AAA screening. Providers who perform the physical and order the AAA screening need to document the AAA risk factors.
Indications for surgery in patients without symptoms are:
- size greater than 5.5 cm in diameter
- "becomes tender"
- grows more than 1 cm in diameter per year
| Aneurysms > 5.0 cm
Mean age 70
|Endovascular||Open repair||Mortality at 6 yrs|| Endo=31%|
| Aneurysms > 5.5 cm
Mean age 74
|Endovascular||Open repair||Mortality at 6 yrs|| Endo=42%|
| Aneurysms > 5.5 cm
Mean age 77
Unfit for open repair
|Endovascular||None||Mortality at 3 yrs|| Endo=74%|
Endovascular repair (i.e., inserting a stent or patch) is a less invasive procedure that may be used when the renal arteries are not part of the aneurysm. Endovascular repair has improved short term outcomes. However, it has similar outcomes as compared to open surgery at two years and six years.
Acute kidney injury
- Anonymous (2015), Abdominal aortic aneurysm (English). Medical Subject Headings. U.S. National Library of Medicine.
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- Society for Vascular Surgery
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