of any artery is traditionally thought of an enlargement of the size of the artery to two times the normal size.
This occurs primarily as a degernative process as the infrarenal aorta has no intramural arteries to repair itself. Expansion occurs at 0.5-0.8 CM a year. AAA have to be followed serially. Stable AAA of the infrarenal aorta should be repaired at 5.5 cm.