Emergency ultrasound of the abdominal aorta by UK emergency physicians: a prospective cohort study

Objective: To establish whether UK emergency physicians could reliably perform focused ultrasound of the abdominal aorta in patients with suspected abdominal aortic aneurysm (AAA). Methods: A prospective cohort study was conducted in the emergency department of a tertiary level UK teaching hospital. All patients who underwent an abdominal aortic ultrasound by an emergency physician during a 12 month period from January to December 2005 were included. The principle outcomes were presence of an AAA (external wall diameter >3 cm) or death from ruptured AAA. Outcome data were obtained from paper and electronic patient records and primary care telephone follow up. Results: 120 focused ultrasound scans looking for AAA were performed by 19 different UK emergency physicians of various grades. Of the 120 scans, 26 (22%) were positive for an AAA, of which 17 cases represented a new diagnosis. Ruptured aneurysms represented 46% (12/26) of all positive scans, of which four patients underwent emergency repair. In the remaining 14 patients the AAA was an incidental finding that was not the reason for their presentation to the emergency department. Emergency ultrasound had a sensitivity of 96.3% (95% confidence interval (CI) 81.0% to 99.9%); a specificity of 100% (95% CI 91.8% to 100%); a negative predictive value of 98.6% (95% CI 88.0% to 99.9%); and positive predictive value of 100% (95% CI 86.8% to 100%) for the detection of AAA. Conclusion: Emergency ultrasound scanning by UK emergency physicians has high sensitivity and specificity for identifying AAA, consistent with international experience.