AAA: Screening

The 2004 Pulitzer Prize for Explanatory Reporting was recently awarded to the Wall Street Journal for a series of articles detailing the heavy but often preventable toll exacted by aortic aneurysms. The impetus for writing the WSJ article was the fortuitous discovery of an aneurysm in one of the authors at age 45. The authors reported that ultrasound screening can detect aneurysm before they can do harm. Several subsequent letters to the editor described how that article had increased public awareness of the diagnosis and in several cases led to life-saving treatment.

Abdominal aortic aneurysms claim more lives than AIDS and most kinds of cancers. AAA is the tenth leading cause of death in older men and most of those deaths are caused by rupture. An aneurysm is defined as a maximal aortic diameter 50% larger than the diameter at the level of the renal arteries. Most AAA’s are asymptomatic unless expansion or rupture is imminent. Up to 40% may be detected by physical examination. The diagnosis may be confirmed by B-mode ultrasound. Ultrasound screening should be considered for individuals at risk.

Who should be screened for aneurysmal disease? The most commonly recognized positive associations with AAA are age, male sex and a smoking history followed by family history, hypertension, and vascular disease. However, smoking accounts for at least 75% of all AAA 4.0 cm or greater in diameter. It is recommended that patients with these risk factors who are older than age 50 years should undergo screening with abdominal examination and ultrasonography.

The accuracy and effectiveness of “quick screen ultrasound” has been demonstrated. Furthermore, the cost effective ratio for such a screening program has been shown to be advantageous.  

Early diagnosis and intervention are crucial. The incidence of AAA has increased over the past two decades but the prognosis for a ruptured AAA remains dismal. (50% die before reaching the hospital and only 50% of those treated survive). Additionally, the cost for elective repair is about 50% of a ruptured repair.

Size correlates with risk of rupture. The estimated risk of rupture is estimated at 11% per year for 5.0 to 5.9cm and 25% per year for aneurysms greater than 6cm. Therefore patients with aneurysms over 4.0cm should be followed frequently and be offered intervention if the aneurysm shows signs of enlargement.