Fever of unknown origin

Abstract

Fever of unknown origin (FUO) in Pediatrics can be defined as an entity in which fever is the main sign, without having reached an etiological diagnosis after more than 7 days, despite the correct performance of the history, physical examination, and first-level complementary tests. In most cases, the cause is an uncommon manifestation of a common disease, especially an infectious disease. Other less frequent causes are inflammatory or autoimmune, followed by a miscellaneous of diseases and finally, malignant diseases. In a significant percentage of cases, a diagnosis is not reached, being this a good predictor of spontaneous resolution without sequelae. Thorough and repeated history-taking and physical examination throughout the evaluation is the essential element in the diagnostic process of FUO. It will allow us to reach the cause or optimize the complementary tests that will lead us to the cause with the least harm to the patient and in an efficient manner. Empirical antibiotic or anti-inflammatory treatment should be avoided in stable patients without a specific diagnostic suspicion, as they could mask findings that would bring us closer to the diagnosis.