Figure 4a. Hyperattenuating bowel loop mimicking active hemorrhage. (a, b) Axial (a) and coronal (b) unenhanced CT scans demonstrate hyperattenuating material completely filling a small bowel loop within the right lower quadrant (arrow). (c, d) Axial (c) and coronal (d) CT angiograms obtained immediately after a and b demonstrate a hyperattenuating loop in the right lower quadrant (arrow) that mimics active hemorrhage. Unfortunately, the CT angiograms were not compared with the unenhanced scans, resulting in incorrect interpretation of this hyperattenuating loop as active hemorrhage. The patient was immediately transferred to the angiography suite for transcatheter embolization. Angiography failed to help detect active hemorrhage.