Incidental findings on computed tomography scans for acute appendicitis: prevalence, costs, and outcome

CT scan is increasingly being used to diagnose appendicitis due to its specificity and literature suggesting its cost-effectiveness. CT scans are associated with incidental findings. We sought to investigate the rates of incidental findings identified on CT scans, the follow-up of these findings, and the added cost associated with this follow-up. A retrospective review of patients who underwent appendectomies for acute appendicitis between 2003 and 2005 was completed at Elmhurst Hospital Center (Elmhurst, NY). Incidental findings were grouped into low and high significance, based on workup or follow-up needed. The diagnostic workup and cost of each incidental finding was ascertained. For patients who did not receive a workup due to lack of follow-up, an estimate of the minimum workup was calculated. Of 1142 patients with acute appendicitis, 876 (77%) had a CT scan. This rate increased over time (from 66% in 2003 to 85% in 2005, P < 0.01) and with age (70% in patients under 20 and 98% in patients over 50, P < 0.001). Incidental findings were common and increased with age (23% in the youngest group vs 78% in patients older than 50, P < 0.001). The cost associated with workup of these incidental findings increased with age as well. The increased use of CT scans is associated with a high rate of incidental findings. These findings are usually of low clinical significance but may require further workup and follow-up. Physicians need to be aware of the high rate of incidental findings, the need for further workup, and the associated costs.