AUTHORS: Fahad Gul, MDand Pranav M. Patel, MD, FACC, FAHA, FSCAI
An abdominal aortic aneurysm (AAA) is a segmental full-thickness dilation of the abdominal aortic artery to at least 50% greater than the normal vessel diameter. The average diameter of a human infrarenal aorta is approximately 2 cm, thus a threshold of 3 cm is commonly considered aneurysmal.1
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Most patients with AAA are asymptomatic, and the condition is discovered on routine examination or serendipitously when ordering studies for other symptoms.7Diagnosis of AAA should be considered in the differential with the following symptoms: Abdominal, back, or flank pain and/or a pulsatile abdominal mass. The differential diagnosis of these symptoms can include aortic dissection, ulcerated aortic plaque, renal colic, mesenteric ischemia, pancreatitis, diverticulitis, peptic ulcer disease, biliary tract disease, and others.
An Axial Unenhanced Computed Tomography (CT) Image (A) Reveals Hyperattenuation Within the Wall of the Aorta (Arrow), the So-Called crescent Sign. An Axial Arterial Phase CT Image (B) Reveals Extravasation of Contrast Material Beyond the Confines of the Aortic Wall (Arrow). A Coronal Maximum Intensity Projection Image (C) Reveals Extraluminal Extravasation of Contrast Material (Arrow), as Well as an Incidentally Noted Thoracic Aortic Dissection (Arrowhead).
From Soto JA, Lucey BC: Emergency radiology, the requisites, ed 2, Philadelphia, 2017, Elsevier.
Not routinely indicated. For suspected infected or inflammatory aneurysms, white blood cell (WBC), erythrocyte sedimentation rate (ESR)/C-reactive protein (CRP), and blood cultures can be considered. An elevated d-dimer may indicate a thrombus within the aneurysm. Fig. 2 describes an algorithm for the diagnosis and treatment of abdominal aortic aneurysms.
Figure 2 Algorithm for the diagnosis and treatment of abdominal aortic aneurysms (AAAs).
BP, Blood pressure; CT, computed tomography; MRI, magnetic resonance imaging; NS, normal saline; PRBCs, packed red blood cells; SBP, systolic blood pressure; US, ultrasonography.
From Adams JG et al: Emergency medicine, clinical essentials, ed 2, Philadelphia, 2013, Elsevier.
Figure 7 Digital subtraction angiogram following endovascular aneurysm repair.
From Fillit HM: Brocklehursts textbook of geriatric medicine and gerontology, ed 8, Philadelphia, 2017, Elsevier.
B, An Image after Endovascular Repair Demonstrates Complete Exclusion of the Aneurysm (Arrowhead) with No Endoleak and Preservation of the Renal and Hypogastric Arteries.
From Soto JA, Lucey BC: Emergency radiology, the requisites, ed 2, Philadelphia, 2017, Elsevier.
An, Aneurysm; Cia, Common Iliac Artery; Eia, External Iliac Artery; IIA, Internal Iliac Artery; In, Infrarenal Neck; Lk, Left Kidney; RA, Renal Artery; Rk, Right Kidney.
From Townsend CM et al [eds]: Sabiston textbook of surgery, ed 17, Philadelphia, 2004, Saunders.
Figure 5 Aneurysm of the abdominal aorta.
A large aortic aneurysm is evident. The aorta exceeds 5 cm in diameter. A large amount of thrombus (T) partially surrounds the contrast-enhanced patent lumen (L). Note the atherosclerotic calcification (arrowhead) in the wall of the aneurysm.
Figure 3 Transverse image of an abdominal aortic aneurysm.
Note the measurements of 3.33 × 3.85 cm. The inferior vena cava is seen to the patient s right of the aorta, and the vertebral body is seen below the two vessels. Note also that there appears to be an echogenic flap within the aorta, possibly representing an aortic dissection.
From Adams JG et al: Emergency medicine, clinical essentials, ed 2, Philadelphia, 2013, Elsevier.