The main artery in the abdomen taking blood from the heart down toward the legs is the aorta. Occasionally this artery will become enlarged, and be at risk for leaking. Sometimes this will cause an emergency and be life threatening, requiring urgent surgery. Often there are no symptoms when the artery is slowly becoming larger, and not leaking, but sometimes it causes a deep low back pain. The pain is not usually brought on with moving around.
The cause is unknown, but may be more common in people who smoke, are overweight, have high blood pressure, diabetes or high cholesterol levels. It is more common in men.
A rapidly enlarging or leaking aorta in the abdomen may cause low back pain. Sometimes there is also abdominal or side pain, which may pulsate with the heartbeat. In addition to severe or sudden abdominal or back pain symptoms there may be light headedness or fainting, and a rapid heartbeat. This situation is an emergency.
The diagnosis may be confirmed by using tests such as an ultrasound, CT scan, MRI, or X-rays of the blood vessel using a dye (angiogram).