Meckel's scan: pitfall in patients with active small bowel bleeding.

Potential for a false-positive Meckel's scan is highlighted in this patient with intermittent, low-volume small bowel bleeding. Meckel's scan showed late appearance of focal activity mimicking a positive diverticulum finding. This was secondary to extravasated tracer during a coincidental bleeding as shown by a Tc-99m tagged red blood cell scan obtained 2 days earlier. Inaccurate diagnosis of Meckel diverticulum was avoided by: 1) noticing the late appearance in relationship to the gastric uptake, and 2) showing motility of the focus on delayed dynamic imaging that confirmed transit of extravasated tracer along the small bowel with peristalsis. Subsequent capsule endoscopy showed a bleeding ulcer in the ileum.