Recent reports have shown that these stress distributions have been shown to correlate to the overall geometry of the AAA rather than solely to the maximum diameter. It is also known that wall stress alone does not completely govern failure as an AAA will usually rupture when the wall stress exceeds the wall strength. In light of this, rupture assessment may be more accurate if both the patient-specific wall stress is coupled together with patient-specific wall strength. A noninvasive method of determining patient-dependent wall strength was recently reported, with more traditional approaches to strength determination via tensile testing performed by other researchers in the field. Some of the more recently proposed AAA rupture-risk assessment methods include: AAA wall stress; AAA expansion rate; degree of asymmetry; presence of intraluminal thrombus (ILT); a rupture potential index (RPI); a finite element analysis rupture index (FEARI); biomechanical factors coupled with computer analysis; growth of ILT; geometrical parameters of the AAA; and also a method of determining AAA growth and rupture based on mathematical models.The postoperative mortality for an already ruptured AAA has slowly decreased over several decades but remains higher than 40%. However, if the AAA is surgically repaired before rupture, the postoperative mortality rate is substantially lower, approximately 1-6%. Epidemiology
The occurrence of AAA varies by ethnicity. In the United Kingdom, the rate of AAA in Caucasian men older than 65 years is about 4.7%, while in Asian men it is 0.45%. It is also less common in individuals of African, and Hispanic heritage.
Ruptured AAA should be suspected in any person older than 60 who experiences collapse, unexplained low blood pressure, or sudden-onset back or abdominal pain. Abdominal pain, shock, and a pulsatile mass is only present in a minority of cases. Although an unstable person with a known aneurysm may undergo surgery without further imaging, the diagnosis will usually be confirmed using CT or ultrasound scanning.The suprarenal aorta normally measures about 0.5 cm larger than the infrarenal aorta. Differential diagnosis
Aortic aneurysm rupture may be mistaken for the pain of kidney stones, or muscle related back pain. Prevention
Smoking cessation
Treatment of hypertension

Screening
The U.S. Preventive Services Task Force (USPSTF) recommends a single screening abdominal ultrasound for abdominal aortic aneurysm in males age 65 to 75 years who have a history of smoking. Among this group who does not smoke, screening may be selective. It is unclear if screening is useful in women who have smoked and the USPSTF recommend against screening in women who have never smoked.In the United Kingdom the NHS AAA Screening Programme invites men in England for screening during the year they turn 65. Men over 65 can contact the programme to arrange to be screened.In Sweden one time screening is recommended in all males over 65 years of age. This has been found to decrease the risk of death from AAA by 42% with a number needed to screen of just over 200.