Rupture may be indicated by the presence of free fluid in the abdomen. A contrast-enhanced abdominal CT scan is the best test to diagnose an AAA and guide treatment options.Only 10–25% of patients survive rupture due to large pre-and postoperative mortality. Annual mortality from ruptured aneurysms in the United States is about 15,000. Most are due to abdominal aneurysms, with thoracic and thoracoabdominal aneurysms making up 1% to 4% of the total. Aortic rupture
An aortic aneurysm can rupture from wall weakness. Aortic rupture is a surgical emergency and has a high mortality even with prompt treatment. Weekend admission for a ruptured aortic aneurysm is associated with increased mortality compared with admission on a weekday, and this is likely due to several factors including a delay in prompt surgical intervention. Risk factors
Coronary artery disease
Hypertension
Loeys-Dietz Syndrome
Hypercholesterolemia
Hyperhomocysteinemia
Elevated C-reactive protein
Tobacco use
Alcohol use
Peripheral vascular disease
Marfan syndrome
Ehlers-Danlos type IVO
Bicuspid Aortic Valve
Syphilis
IgG4-related disease
Pregnancy
Chronic obstructive sleep apnea
Psoriasis

Pathophysiology
An aortic aneurysm can occur as a result of trauma, infection, or, most commonly, from an intrinsic abnormality in the elastin and collagen components of the aortic wall. While definite genetic abnormalities were identified in true genetic syndromes (Marfan, Elher-Danlos and others) associated with aortic aneurysms, both thoracic and abdominal aortic aneurysms demonstrate a strong genetic component in their aetiology. Prevention
The risk of aneurysm enlargement may be diminished with attention to the patients blood pressure, smoking and cholesterol levels. There have been proposals to introduce ultrasound scans as a screening tool for those most at risk: men over the age of 65.
Abdominal aortic aneurysm
Abdominal aortic aneurysms (AAAs) are more common than their thoracic counterpart. One reason for this is that elastin, the principal load-bearing protein present in the wall of the aorta, is reduced in the abdominal aorta as compared to the thoracic aorta. Another is that the abdominal aorta does not possess vasa vasorum, the nutrient-supplying blood vessels within the wall of the aorta. Most AAA are true aneurysms that involve all three layers (tunica intima, tunica media and tunica adventitia). The prevalence of AAAs increases with age, with an average age of 65–70 at the time of diagnosis. AAAs have been attributed to atherosclerosis, though other factors are involved in their formation. The risk of rupture of an AAA is related to its diameter; once the aneurysm reaches about 5 cm, the yearly risk of rupture may exceed the risks of surgical repair for an average-risk patient. Rupture risk is also related to shape; so-called "fusiform" (long) aneurysms are considered less rupture-prone than "saccular" (shorter, bulbous) aneurysms, the latter having more wall tension in a particular location in the aneurysm wall.Before rupture, an AAA may present as a large, pulsatile mass above the umbilicus. A bruit may be heard from the turbulent flow in the aneurysm. Unfortunately, however, rupture may be the first hint of AAA. Once an aneurysm has ruptured, it presents with classic symptoms of abdominal pain which is severe, constant, and radiating to the back.The diagnosis of an abdominal aortic aneurysm can be confirmed at the bedside by the use of ultrasound.