Figure 5a. Active left colonic diverticular hemorrhage. (a, b) Axial (a) and coronal (b) 3-mm maximum-intensity-projection (MIP) CT angiographic images demonstrate a swirling jet of extravasated contrast material within the lumen of the descending colon (arrow). Multiple colonic diverticuli were also seen, and diverticular bleeding was suspected. (c) Angiogram obtained during microcoil embolization of bleeding left colic artery branches shows puddling of contrast material within the left colon (arrow), a finding that represents hemorrhage. Subsequent colonoscopy performed after bowel preparation revealed multiple large diverticuli within the descending colon, several of which contained blood. No active hemorrhage was seen at colonoscopy.