Gastrointestinal tract radionuclide activity on In-111 labeled leukocyte imaging: clinical significance in patients with fever of unknown origin.

To determine the frequency and clinical significance of indium-111 labeled leukocyte activity in the gastrointestinal (GI) tract of patients with fever of unknown origin, we reviewed 312 leukocyte studies involving 271 patients. Radionuclide activity was noted in the bowel in 59 cases. Of these, only 27 were due to the infection or inflammatory disease that caused the patient's fever. The 32 false-positive results were due primarily to swallowed leukocytes or bleeding. In two cases, no explanation was found for the activity in the GI tract. We conclude that bowel activity on In-111 labeled leukocyte scans in patients with fever of unknown origin often does not correlate with the true cause of the patient's fever.