Utilization of CT for Extremity Cellulitis: A Retrospective Single-Center Analysis

Routine imaging of soft tissue infection is not recommended and represents a potential area of CT overuse. The utility of CT in patients with superficial soft tissue infection of the extremities is unknown. The purpose of this study is to evaluate the utilization and clinical impact of CT ordered in the setting of extremity cellulitis.

We retrospectively analyzed patients with extremity cellulitis examined with CT between 2012 and 2021 at a single center. We collected patient history, diagnostic imaging characteristics, and subsequent surgery decision. We hypothesized that yield of CT for deep infection was significantly lower than 10% and that yield was decreasing over time. These hypotheses were evaluated with Rao-Scott χ² tests and repeated measures logistic regression.

There were 496 eligible encounters among 463 patients. Yield of positive CT among lower extremity patients was 5.5% (95% confidence interval 3.33-7.75), significantly less than our hypothesis of 10% (P = .003). In 71.8% of encounters, patients underwent diagnostic imaging studies in addition to CT. Utilization rose from 0.08% per hospital visit in 2012 to 2013 to 0.14% in 2020 to 2021, with differences in yield between time periods not reaching statistical significance (P = .059). Among 496 encounters, 62 received surgery (12.1%), with 21 of these cases preceded by a positive CT for deep infection.

Our 10-year single-center analysis of CT use for extremity cellulitis demonstrated a low yield of positive CT findings for deep infection and limited impact of CT on surgical management. A high incidence of patients undergoing multiple radiologic examinations suggests uncertainty in selecting appropriate imaging modalities in this clinical scenario.

This single-center retrospective analysis found that CT examination of patients with clinically diagnosed cellulitis of the extremities has significantly low yield for deep infection in the lower extremities.