Relevance of CT for the detection of septic foci: diagnostic performance in a retrospective cohort of medical intensive care patients

Abstract

Aim: To analyse the diagnostic yield of computed tomography (CT) in septic patients from a medical intensive care unit (ICU).

Materials and methods: A full-text search of the department's radiological information system (RIS) retrieved 227 body CT examinations undertaken to search for a septic focus in 2018 from medical ICU patients. CT reports were categorised according to the identified foci. Clinical and laboratory information was gathered. Data were analysed statistically using descriptive statistics, diagnostic test quality criteria, binomial tests and chi-square test.

Results: A total of 227 CT examinations from 165 septic patients detected 264 foci, which were distributed as follows: 58.3% (n=154/264) chest, 26.5% (n=70/264) abdomen, 5.3% (n=14/264) genitourinary system, and 9.8% (n=26/264) other body regions. In 15.9% (n=36/227) no focus was identified on CT. Based on CT reports, 37.5% (n=99/264) of foci were graded as certain, 18.9% (n=50/264) as likely, and 15.9% (n=42/264) as possible infectious sources. Septic foci were detected using CT with 75.8% sensitivity (95% confidence interval [CI] 69.6-81.9%) and 59.46% specificity (95% CI 42.9-76.1%). The positive predictive value was 90.6% (95% CI 86-95.2%), with a negative predictive value of 32.4% (95% CI 21-43.8%).

Conclusion: The present results confirm that body CT is a suitable rule-in test for septic patients in medical intensive care, although it cannot reliably rule out a septic focus. Follow-up CT examinations may reveal a septic source in the further course of a patient's hospital stay.