Does a normal screening ultrasound of the abdominal aorta reduce the likelihood of rupture in emergency department patients?

INTRODUCTION

Abdominal aortic aneurysm (AAA) development is a multifactorial process that is more prevalent among people ≥65years of age. Major risk factors are obesity, male sex, history of smoking (at least 100 cigarettes in a person's lifetime), and history of AAA in a first-degree relative. The United States Preventative Task Force has recommended a one-time ultrasound screening for men aged 65-75years. Based on studies, negative results on a single ultrasound examination around the age of 65years appear to virtually exclude the risk for future AAA rupture or death. While ultrasonography (US) is the confirmatory study of choice, computed tomography (CT) can also be used in the diagnosis of AAA. The goal of this study is to determine if AAA rupture can reliably be excluded in individuals with abdominal pain who have had a normal caliber aorta on CT or US after the age of 65years.

MATERIALS AND METHODS

A retrospective study (approved by institutional review board) of emergency department (ED) patients in an urban academic center was performed. Subjects were included if they met the following criteria: age ≥65years; an initial CT or US as an ED patient, inpatient, or outpatient for any indication, which identified an abdominal aorta <3cm; and a second CT or US during an ED visit. The incidence of ruptured AAA on the second CT or US with a history of normal aortic caliber was identified.

RESULTS

During the study period, 606 subjects were enrolled. Demographic data are listed in Table 1. Three subjects (0.5%) exhibited an abnormal-sized aorta on ED evaluation. None of these three subjects had an AAA intervention. The average size of the abnormal aorta in these three subjects was 3.3cm (S.D. 0.17).

CONCLUSION

Based on these results, it appears that AAA and rupture may reliably be excluded in ED patients with abdominal pain who have previously had a normal caliber aorta on CT or US after the age of 65years. A prospective, multicenter study would help validate these findings.