Asymptomatic abdominal aortic aneurysms can cause death from rupture. If detected by abdominal imaging, these aneurysms can be repaired electively before rupture occurs. Some experts have called for ultrasonography and abdominal palpation to detect these aneurysms. Lederle reviewed the literature and consulted with the directors of trials and other experts to evaluate the potential benefit of screening for asymptomatic abdominal aortic aneurysms.
These aneurysms occur in 4 to 8 percent of older men. Rupture causes approximately 9,000 deaths annually in the United States, and small asymptomatic aneurysms typically increase in diameter by 0.08 to 0.12 in (0.2 to 0.3 cm) per year until rupture, which usually occurs at a diameter of 2.4 in (6.0 cm) or greater. Lederle assumes that there will be a 5- to 10-year interval before a typical 1.2-in (3.0-cm) aneurysm develops symptoms of rupture. Elective repair, which has an operative mortality of 4 to 6 percent, could be done during this period. Only 20 percent of patients survive a rupture.
Ultrasonography has a sensitivity and a specificity of nearly 100 percent for abdominal aortic aneurysms and can be performed quickly. Occurrence of these aneurysms is more common in men, and rupture rarely occurs before 65 years of age; therefore, men usually are screened at age 65 and older. Smoking is another risk factor for aneurysm. Four randomized trials of one-time screening using rupture as an end point noted reductions in aneurysm-related mortality of 21 to 68 percent with screening. The few studies that have looked at repeat screening have not demonstrated any advantage over one-time screening of men older than 65 years. Patients with unrepaired aneurysms probably should have repeated examinations over time. Medical treatment for these small aneurysms is under investigation.
Elective surgical repair in an otherwise healthy man is indicated when an asymptomatic aneurysm is greater than 2.2 in (5.5 cm) in diameter. Endovascular repair using an expandable graft inserted through the femoral or iliac arteries is becoming a second option to standard open repair. Screening risks include worry and unnecessary procedures.
The author concludes that it is reasonable to offer screening to men 65 to 79 years of age who have ever smoked, while reserving elective repair for those with aneurysms 2.2 in or larger. Currently, the Canadian Task Force on the Periodic Health Examination and the U.S. Preventive Services Task Force give screening a C rating (poor evidence to include or exclude in periodic examination). These organizational recommendations are being reconsidered in response to the results of recent trials. Many insurers do not cover routine screening.