Suspected infection of unclear origin at the emergency department: diagnostic yield of thoraco-abdominal-pelvic CT in non-severe patients.

Abstract

Objectives: To assess the diagnostic yield of thoraco-abdominal-pelvic CT (TAP-CT) in suspected infection of unclear origin in the Emergency Department (ED) and identify predictive factors for normal TAP-CT to optimize its use.

Methods: We retrospectively categorized 517 TAP-CT studies of adult patients with non-severe infection of unclear origin based on the presence of an infectious focus or significant findings, such as neoplasia or thrombosis. Descriptive analysis, correspondence assessment between CT results and final diagnosis, and statistical modeling were performed to identify predictors of normal TAP-CT.

Results: An infectious focus was identified in 55% TAP-CT scans, mainly pulmonary (46%), bilio-digestive (25%), and genitourinary (23%). Significant noninfectious findings were detected in 20%, including thrombosis (7%) and neoplasia (12%). TAP-CT showed a sensitivity of 73%, specificity of 88%, PPV of 94%, and NPV of 57%, with moderate agreement (Kappa= 0.53) between TAP-CT findings and final diagnosis. Overall, 67% of patients had an identifiable cause for infection-like symptoms. Although C-reactive protein <128 mg/L was associated with normal TAP-CT, no model reliably predicted a normal scan.

Conclusions: TAP-CT identified a relevant finding in over two-thirds of cases, reinforcing its role in diagnosing both infectious and mimicking conditions. No specific criteria could safely exclude TAP-CT, making it a valuable tool for managing patients with suspected infections of unclear origin.

Advances in knowledge: This study is the first to assess TAP-CT's value in suspected non-severe infections of unclear origin in the ED, highlighting its role in detecting infectious and noninfectious conditions and optimizing diagnostic strategies.