Pediatricians often confuse fever without a source and fever of unknown origin.

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Fever is a common complaint in children. In most cases, fevers are due to self-limited viral infections and require no more than symptomatic treatment. Sometimes fever is due to common bacterial infections that are diagnosed by history and physical examination and require antibiotic treatment without laboratory evaluation. In a few clinical situations, the cause of fever is not easily identified. Fever without a source (FWS) may need further evaluation that includes laboratory tests or imaging. Rarely, the fever is more prolonged, requires more intensive evaluation, and falls in the category of fever of unknown origin (FUO).

There is often confusion about the terms FUO and FWS. Distinguishing between FUO and FWS is important and is based on duration of fever. FWS can progress to FUO if no cause is...

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