1,
TABLE 16.1 Common causes of pyrexia of unknown origin
History
The history may give a number of clues in these puzzling cases. In some patients a careful history may give the diagnosis where expensive tests have failed. See
Questions box 16.1
General questions to ask the patient with a fever
! denotes symptoms for the possible diagnosis of an urgent or dangerous problem.
The time course of the fever and any associated symptoms must be uncovered. Symptoms from the various body systems should be sought methodically.
Details of any recent overseas travel are important. Find out also about hobbies and exposure to pets. Occupational exposure may be important. Take a drug history. Find out if the patient is involved in behaviour posing a risk of HIV infection. Patients who are already in hospital may have infected cannulas or old cannula sites.
Fever due to bacteraemia (the presence of organisms in the bloodstream) is associated with a higher risk of mortality. It is present in up to 20% of hospital patients with fever.
GOOD SIGNS GUIDE 16.1 Clinical findings and bacteraemia
Risk factors | Likelihood ratio if | |
Present | Absent | |
Age > 50 | 1.4 | 0.3 |
Temperature >38.5 | 1.2 | NS |
Rigors | 1.8 | NS |
Tachycardia | 1.2 | NS |
Respiratory rate >20 | NS | NS |
Hypotension | 2.0 | NS |
Chronic kidney disease | 4.6 | 0.8 |
Hospitalisation for trauma | 3.0 | NS |
Terminal disease | 2.7 | NS |
Indwelling urinary catheter | 2.4 | NS |
Central venous catheter | 2.0 | NS |
‘Toxic appearance’ | NS | NS |
From McGee S, Evidence-based physical diagnosis, 2nd edn. St Louis: Saunders, 2007.
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