Prognostic significance of late imaging results in technetium-99m-labeled red blood cell gastrointestinal bleeding studies with early negative images.

The prognostic significance of the results of late imaging in patients with early negative 99mTc-labeled red blood cell (RBC) gastrointestinal (GI) bleeding studies was examined in a retrospective review of studies performed on 48 patients. Twenty-two studies showed intraluminal accumulation of labeled RBCs only on late images acquired from 3-24 hr following RBC injection. Patients with late positive studies had larger transfusion requirements than those with negative late images (mean total units transfused: 7.3 versus 3.5 (p less than 0.05); mean units transfused following scan commencement: 4.5 versus 2.0 (p less than 0.005)). Patients with late positive studies more frequently required angiography (3/22 versus 0/26) and surgery (5/22 versus 2/26). Sites of bleeding were more commonly identified in the stomach or small bowel in patients with late positive studies, while colon bleeding sources were more commonly found in those with late negative studies. The location of intraluminal blood on late images did not reliably discriminate upper from lower tract hemorrhage. In patients with early negative GI bleeding studies, results of later imaging provide objective evidence of the presence or absence of continued intermittent hemorrhage, and suggest both the region of bowel responsible and the relative risk for requiring further invasive procedures.