Epidemiologic Criteria:
- Fever x 3 weeks (38.3)
- Failure to find cause despite appropriate initial outpatient/inpatient investigations
Causes:
- Majority unknown
- Then infection (most commonly TB or occult abscesses), inflammatory, malignancy, other
Diagnostic tests (beyond initial):
- CT abdomen to look for abscess, lymphadenopathy, other pathology. Yield ~20%
- Bone scan (insensitive, but specific with good + LR)
- Liver biopsy -- regardless of hepatomegaly or LFT abnormalities has yield ~15%
- Temporal artery biopsy in the elderly -- yield ~ 15%
- Leg dopplers -- yield 2-6%
- Bone marrow biopsy-- in those with cytopenias or compatable syndromes. Yield ~1%
