Aneurysm is defined as increase in the diameter of any blood vessel of the body. Abdominal aortic aneurysm is the most commonly occurring aneurysm affecting the largest artery of the body, the aorta. The diameter of the aorta is about 2cm; when it increases to about 3 cm it is considered to be an aneurysm and when the diameter increases to greater than 5.5 cm the aneurysm is considered to be large and is at increased risk of rupture.In most of the patients abdominal aortic aneurysm does not produce any symptom (asymptomatic) however sometimes symptoms like abdominal or back pain due to pressure on the adjacent structures due to increase in the bulk of the aneurysm. Pain in the legs is also another presenting symptom occurring due to pressure on the blood vessels supplying the legs.

Rupture of the aneurysm resulting into heavy blood loss may kill the person. Surgery is the only treatment option available other than watchful monitoring in smaller, very slowly or not at all growing their farms.Abdominal aortic aneurysm is mostly seen in elderly men aged between 65 and 75 years of age and with past history of smoking.

Causes
The exact cause of abdominal aortic aneurysm is not known but the commonly associated factors with the condition are
1) Tobacco: use of tobacco in any form as during cigarette smoking, by chewing etc. Tobacco increases the accumulation of fatty substance along the inner lining of the aorta (atherosclerosis) at the expense of elasticity of the vessel. Hence the walls of the aorta becomes stiff and damaged and thus hastening the enlargement of the aneurysm.
2) Atherosclerosis or abnormal fat deposit along the inner wall is one of the commonest contributing factors of enlargement and development of aneurysm.
3) Under rare circumstances abdominal aortic aneurysm may occur following infection of inflammation of the lining of the artery (vasculitis) and thus weakening of a particular part of the aorta.

Risk factors
Common risk factors for abdominal aortic aneurysm include
1) Age: advance age in one of the most important risk factors as these condition is mostly diagnosed in males beyond 65 years
2) Chronic use of tobacco in any form as during smoking cigarettes or during chewing tobacco etc
3) Family history: positive family history for abdominal aortic aneurysm is also very important as this disease seem to run in families
4) Male
5) Atherosclerosis etc.

Treatment
Treatment of abdominal aortic aneurysm depend upon the mainly on the size, location of the aneurysm, general health of the patient, associated diseases, if any, kidney function etc. In case of small aneurysm with size less than 4 cm without any symptoms watchful monitoring with periodic evaluation by ultrasound are recommended. Any aneurysm greater than 4 to 5.3 cm in size is considered to be medium aneurysm and vice versa. In rapidly growing, large, leaky aneurysm surgery is the only treatment available. In comparison to open surgery endovascular surgery is much preferred as mortality rate following endovascular is very low.