James B. Lewis Jr, MD

A methodical approach to diagnosis usually reveals the cause of fever. In patients with simple fever, a careful history taking and physical examination combined with basic laboratory and imaging studies (complete blood cell count with differential, urinalysis, and possibly a chest film and blood cultures) usually yield the diagnosis. In patients with prolonged fever whose cause remains undiagnosed after extensive examination (fever of unknown origin), repeat the history taking and physical examination; also order routine laboratory studies, an HIV test, a tuberculin skin test, 3 sets of blood cultures, and chest films. In addition, abdominal CT scanning is often useful. Further testing at this point may include fluorodeoxyglucose positron emission tomography, technetium-tagged white blood cell scanning, transesophageal echocardiography, liver biopsy, bone marrow examination, and/or temporal artery biopsy. Exploratory laparotomy is rarely indicated.