Rupture in small abdominal aortic aneurysms

The decision of whether to repair small abdominal aortic aneurysms (AAAs), which are those that are less than 5 cm in diameter, remains controversial.

We describe 161 consecutive patients who were seen at a single urban hospital with ruptured AAAs (rAAAs) and in whom aneurysm size was measured with ultrasound scanning, or rarely computed tomography, en route to the operating room. Eleven patients (6.8%) had AAAs that measured less than 5.0 cm. This group was compared with 150 patients who had rAAAs that were more than 5 cm.

The mortality rates were similar in both of the groups 70% for small rAAAs versus 66% for large rAAAs. No significant differences were seen between the patients with small and large ruptured aneurysms with respect to the prevalence rates of hypertension (60% vs 50%) or of cardiac disease (20% vs 22%). However, the prevalence rate of obstructive lung disease was significantly different (64% vs 25%; P =.02) as was the rate of diabetes (28% vs 3%; P =.004). Five aneurysms were measured at exactly 5 cm. This suggests that approximately 10% of all aneurysms that rupture in this series do so at 5 cm or less.

In view of the safety of elective repair as compared with the prohibitive risk associated with aneurysm rupture, patients who are at good risk with small AAA (between 4 and 5 cm) should be considered for elective aneurysm resection. For unclear reasons, obstructive lung disease and diabetes are associated with a significantly greater risk for rupture of small AAA. Patients with these risk factors should be given special consideration.