Fever of unknown origin

Petersdorf and Beeson criteria:
1) Fever higher than 38.3°C (101°F) on several occasions
2) Persisting without diagnosis for at least 3 weeks
3) At least 1 week's investigation in hospital
Work up:
1) comprehensive histpry with repeated PE
2) laboratory tests: serological, blood culture, immunological
3) studies: U/S to r/o cholelithiasis, echo to r/o endocarditis, CT-scan to r/o infection, abscess, malilgnency. Gallium-67 scanning which seems to visualize chronic infections more effectively.
4) invasive techniques : biopsy and laparotomy for pathological and bacteriological examination
5) PET scan: has been reported to have sensitivity of 84% and a specificity of 86% for localizing the source of fever of unknown origin.
6) systematic discontinuation of medications to r/o drug fever