An abdominal aneurysm is a bulge in the abdominal segment of the aorta, the major blood vessel leaving the heart. The bulge indicates a weak spot in the abdominal aorta that threatens to rupture, leading to catastrophic internal bleeding. According to the Merck Manual, when an abdominal aortic aneurysm (AAA) is detected early, in most cases medicines or surgery can successfully treat it. However, rupture or bursting of the AAA is a life-threatening emergency that requires immediate treatment.
Risk
An aneurysm occurs when an artery bulges to 50 percent greater than its normal size. According to the Merck Manual, an abdominal aortic aneurysm has a circumference of greater than 3 cm. Larger AAAs carry a greater risk for rupture. The Merck Manual states that there is no risk for rupture for AAAs of less than 4 cm in diameter. The risk increases to 10 percent to 20 percent per year when the AAA is 6.0 to 6.9 cm in diameter and 30 percent to 50 percent per year when the AAA is 8 cm or more in diameter.
Warning Signs
Someone with an AAA might never know that they have one because often there are no symptoms until the aneurysm bursts, says the Mayo Clinic. When an AAA grows rapidly or is on the verge of bursting, the abdomen might feel tender. The patient might experience a deep, steady, gnawing pain in the abdomen or lower back, according to the National Heart Lung and Blood Institute.
Cause
An AAA can rupture spontaneously, as the weak spot in the aorta ultimately fails to withstand the pressure of blood rushing through it. In some cases, an added force can precipitate the rupture. The strain of lifting something heavy, or a blow to the abdomen can be the final straw the makes the aneurysm burst.
Symptoms
At the moment of rupture the patient experiences sudden, severe pain in the lower back and abdomen. As blood gushes out of the aorta and blood pressure plummets, the patient feels light-headed, dizzy and nauseated; the skin will be clammy, sweaty and pale. To compensate for the rapid blood loss, the heart races. The patient has a weak, rapid pulse. As blood loss continues the patient shows signs of shock such as shallow breathing and bluish discoloration of the lips and fingernails due to low oxygen levels. Eventually the patient loses consciousness.
Prognosis
The Merck Manual warns that most people with a ruptured AAA die without immediate emergency surgery, and according to the Mayo Clinic, the odds of surviving the emergency surgery are not good. The Mayo Clinic also says that most people die from a ruptured AAA before ever reaching the hospital.
