Fever of unknown origin, FUO


FUO is defined as Fever >38.3°C (101°F) on at least two occasions, illness duration of ≥3 weeks, and the diagnosis that remains uncertain after a thorough history-taking, physical examination, and the basic investigations. It usually bothers patients a lot. Patients seek medical help frequently and usually take antibiotics to ease their anxieties.

Infection, neoplasms and noninfectious inflammatory diseases are the main etiologies of FUO. Noninfectious inflammatory diseases includes collagen or rheumatic diseases, vasculitis syndromes, and granulomatous disorders. Miscellaneous causes and unknown etiology can also be diagnosed finally.



It is essential to get the correct diagnosis of FUO. Patients can be treated precisely after the exact diagnosis of FUO. The exact diagnosis can prevent the unnecessary use of antibiotics that are usually prescribed by the physicians. The good outcome in patients without a diagnosis confirms that potentially lethal occult diseases are very unusual and that empirical therapy is rarely required in stable patients.



The diagnostic workup includes the search for potentially diagnostic clues through complete and repeated history-taking and physical examination and the obligatory investigations from blood samples. Extensive microbiology studies from blood or body fluid are necessary. Other studies include computed tomography of chest, abdomen and pelvis, echocardiography and 18F-fluorodeoxyglu­cose (FDG) positron emission tomography. Biopies of bone marrow, lymph nodes, liver biopsy, and the possible involved organs are sometimes needed.



There are minimal risks and complications during the diagnostic process. The risks and complications, including bleeding and the formation of hematoma, come from the biopsy of the suspicious lesion identified by the image study. They can be managed immediately and do not result in disabilities.


Estimated Cost

Around 200,000 NTD and the cost for the treatment is depend on the final diagnosis.