title: The role of invasive and non-invasive procedures in diagnosing fever of unknown origin.
abstract: BACKGROUND
  The etiology of fever of unknown origin has changed because of the recent advances in and widespread use of invasive and non-invasive diagnostic tools. However, undiagnosed patients still constitute a significant number.
  
  
  OBJECTIVE
  To determine the etiological distribution and role of non-invasive and invasive diagnostic tools in the diagnosis of fever of unknown origin.
  
  
  METHODS
  One hundred patients who were hospitalized between June 2001 and 2009 with a fever of unknown origin were included in this study. Clinical and laboratory data were collected from the patients' medical records retrospectively.
  
  
  RESULTS
  Fifty three percent of the patients were male, with a mean age of 45 years. The etiology of fever was determined to be infectious diseases in 26, collagen vascular diseases in 38, neoplastic diseases in 14, miscellaneous in 2 and undiagnosed in 20 patients. When the etiologic distribution was analyzed over time, it was noted that the rate of infectious diseases decreased, whereas the rate of rheumatological and undiagnosed diseases relatively increased because of the advances in imaging and microbiological studies. Seventy patients had a definitive diagnosis, whereas 10 patients had a possible diagnosis. The diagnoses were established based on clinical features and non-invasive tests for 61% of the patients and diagnostic benefit was obtained for 49% of the patients undergoing invasive tests. Biopsy procedures contributed a rate of 42% to diagnoses in patients who received biopsies.
  
  
  CONCLUSIONS
  Clinical features (such as detailed medical history-taking and physical examination) may contribute to diagnoses, particularly in cases of collagen vascular diseases. Imaging studies exhibit certain pathologies that guide invasive studies. Biopsy procedures contribute greatly to diagnoses, particularly for malignancies and infectious diseases that are not diagnosed by non-invasive procedures.
authors.affiliation: Department of Infectious Diseases and Clinical Microbiology, Istanbul University Cerrahpasa Medical Faculty, Istanbul/Turkey. bigimete@yahoo.com
authors.forename: Bilgul
authors.initials: B
authors.lastname: Mete
authors.forename: Ersin
authors.initials: E
authors.lastname: Vanli
authors.forename: Mucahit
authors.initials: M
authors.lastname: Yemisen
authors.forename: Ilker Inanc
authors.initials: II
authors.lastname: Balkan
authors.forename: Hilal
authors.initials: H
authors.lastname: Dagtekin
authors.forename: Resat
authors.initials: R
authors.lastname: Ozaras
authors.forename: Nese
authors.initials: N
authors.lastname: Saltoglu
authors.forename: Ali
authors.initials: A
authors.lastname: Mert
authors.forename: Recep
authors.initials: R
authors.lastname: Ozturk
authors.forename: Fehmi
authors.initials: F
authors.lastname: Tabak
mesh_terms: D005335:Fever of Unknown Origin / Q000175:diagnosis*; D006801:Humans; D008875:Middle Aged; D016133:Polymerase Chain Reaction
keywords: fever of unknown origin; invasive investigations; non-invasive techniques