Pyrexia of unknown origin--approach to management.

Pyrexia of unknown origin (PUO) remains one of the major diagnostic challenges for the clinician. Although infection, malignancy and collagen vascular disease remain the 3 most important causes of PUO, the relative importance of different disease entities within each of these major categories has changed because of improvements in serodiagnosis, culture techniques and radiologic imaging modalities. A detailed clinical history and meticulous physical examination remain the mainstay of the approach to management of patients with PUO. There is no set of "routine" investigations that patients with PUO should be subjected to. Instead, diagnostic testing should be individualised and guided by abnormalities found on clinical examination and simple laboratory testing. In patients in whom the diagnosis remains obscure in spite of extensive investigations and in whom the disease process is clearly progressive, judicious use of narrow spectrum anti-microbial therapy may be warranted. In the majority of the other patients who remain stable, careful clinical observation for new symptoms and signs are advised in the place of multiple courses of antimicrobials.