ACR Appropriateness Criteria® Fever Without Source or Unknown Origin-Child: 2024 Update.

Fever is the most common reason for the evaluation of pediatric patients in acute care settings. Patients for whom no source of infection is identified after a thorough history, physical examination, and laboratory evaluation are classified as having fever without source. Special considerations should be taken in the evaluation of neonates and neutropenic patients as they are at higher risk of serious bacterial infection. Patients with prolonged fever lasting >3 weeks who have no identifiable source of fever are classified with fever of unknown origin and represent an additional subset of febrile pediatric patients that also require special consideration. This document summarizes the relevant literature and provides expert recommendations for the selection of the initial imaging in four common clinical scenarios in pediatric patients with fever without source or unknown origin. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.