Figure 7b. Active arterial extravasation. Note the sentinel clot sign produced by serpiginous areas of high attenuation surrounded by lower-attenuation areas of hematoma. (a) Contrast-enhanced CT image shows active bleeding from a branch of the internal iliac artery (arrow) in a patient with pelvic fractures. (b) Contrast-enhanced CT image shows active bleeding from a splenic rupture due to blunt trauma.