Definition of Aneurysm:

An aneurysm is an abnormal widening or ballooning of a portion of an artery due to weakness in the wall of the blood vessel.

See also:

• Abdominal aortic aneurysm
• Cerebral aneurysm
• Thoracic aortic aneurysm

Causes, incidence, and risk factors:

It is not clear exactly what causes aneurysms. Some aneurysms are present at birth (congenital). Defects in some of the parts of the artery wall may be responsible.

Common locations for aneurysms include:

• The major artery from the heart (the aorta)
• The brain (cerebral aneurysm)
• In the leg behind the knee popliteal artery aneurysm)
• Intestine (mesenteric artery aneurysm)
• An artery in the spleen (splenic artery aneurysm)

High blood pressure, high cholesterol, and cigarette smoking may raise your risk of certain types of aneurysms. High blood pressure is thought to play a role in abdominal aortic aneurysms. Atherosclerotic disease (cholesterol buildup in arteries) may also lead to the formation of some aneurysms.

Pregnancy is often linked to the formation and rupture of splenic artery aneurysms.