Potentially avoidable computed tomography after positive ultrasonography in appendicitis

The aim of this study was to determine the frequency of computed tomography performed despite a positive ultrasonography in histopathologically confirmed appendicitis (potentially avoidable computed tomography), and to assess its effects on radiation exposure, cost, and emergency department length of stay.

This single-center retrospective cohort study included 887 consecutive patients who underwent appendectomy for suspected appendicitis (January 2023-December 2025). Potentially avoidable computed tomography was defined as computed tomography following a positive ultrasonography result. As length of stay was non-normal, imaging strategies were compared using the Kruskal-Wallis test, and length of stay predictors were modeled using median (quantile) regression, with a log-link gamma generalized linear model as a sensitivity analysis. Imaging cost used national tariffs; radiation was estimated as ~8 mSv per abdominal computed tomography with age-specific BEIR VII multipliers.

Computed tomography was used in 87.6% (777/887) of cases. Of the 521 patients who underwent ultrasonography, the results were positive in 35.5%, inconclusive in 30.7%, and negative in 33.8% of cases. Potentially avoidable computed tomography was performed in 81/777 computed tomography examinations (10.4%). Notably, 43.8% (81/185) of patients with positive ultrasonography results subsequently underwent computed tomography scan, corresponding to ~648 mSv of avoidable radiation exposure and an associated cost of 26,667 TL (~US$811), with 49.4% of the affected patients being children. Length of stay did not differ across strategies (p=0.748), and computed tomography was not an independent length of stay predictor (+7.2 min; p=0.23), whereas business-hour arrival was (+15.3 min; p<0.001).

Computed tomography remained frequent even after ultrasonography established the diagnosis, with no effect on emergency department length of stay, generating avoidable radiation and costs concentrated in children. Reducing computed tomography after a positive ultrasonography is a feasible opportunity to improve resource utilization while preserving patient safety.