Very clear example of a positive GI bleeding study, with active extravasation of contrast from a sigmoid diverticulum. The dispersement/diffusion of contrast on delayed images is characteristic, and how this can be differentiated from artifact from dense stool. 

A comment/critique on the technique: Many GI bleeding protocols include a non-contrast phase, which can be helpful for excluding dense material in stool as a potential source of bleeding. However, this is probably not needed in most cases and increases the radiation dose. Also, oral contrast should not have been given, which could clearly obscure a small intestinal source of bleeding. Fortunately, only a small amount of contrast is in the cecum in this case.