Fever of unknown origin (FUO): report on 53 patients in a Dutch university hospital.

Data on patients with fever of unknown origin (FUO) show that the problem of FUO differs, depending on place and time. To obtain a better insight into FUO in the Netherlands, we performed a retrospective study in our University Hospital. We studied 53 patients fulfilling FUO criteria. Infection was found in 11 patients (21%), neoplasms in 10 cases (19%), non-infectious inflammatory diseases in 12 patients (23%). In 16 patients (30%) no diagnosis could be made. In 12 patients fever subsided. In 4 patients fever persisted with a median follow-up of 14.5 years. In all 5 patients without directional clues no diagnosis could be made. In 21 patients (57%) the diagnosis was found by non-invasive methods, in 16 patients (43%) invasive methods were necessary. A median of 54 investigations were done in all patients. The spectrum of FUO is changing. The proportion of patients in whom no diagnosis can be made is growing. The presence of directional clues seems to be an important issue, which other series often do not mention. Their importance should be studied in a larger, prospective study. The use of sophisticated diagnostic techniques seems to be extensive. Because very little is known about the diagnostic yield of many of those techniques, a prospective study on this aspect is needed.