Imaging utilization affects negative appendectomy rates in appendicitis: An ACS-NSQIP study.

Background: Negative appendectomy rates (NAR) historically ranged from 15 to 25%, but have decreased recently.

Methods: Using the 2016 ACS-NSQIP database, we identified patients who underwent appendectomies for appendicitis. Patients with and without appendicitis on pathology were compared. Multivariate analysis was used to identify predictors of negative appendectomies.

Results: 11,841 patients underwent appendectomies, with a NAR of 4.5%. Utilization rates of US, CT and MRI were 14.9%, 86.1%, and 1.1%. NAR's of US, CT, and MRI were 9.7%, 2.5%, and 7.1%, and 19.2% for patients without imaging. An ultrasound consistent with appendicitis has a NAR of 4.8%; adding a CT decreases it to 0.6%. Predictors of NA include females, smoking, no imaging, and ultrasounds. Factors with lower odds of NA include leukocytosis, sepsis, and CTs.

Conclusions: The NAR in the 2016 ACS-NSQIP population is 4.5%. CTs are the most frequently used imaging modality and have the lowest NAR. Obtaining a CT in addition to an ultrasound is associated with lower NAR. This should be further explored with a cost-benefit analysis between multiple imaging studies versus negative appendectomies.