The FAST exam is tried and true for trauma, but in the past it hasn't been super useful for patients with isolated pelvic fractures. This study teases out a very sick subset of this population - patient who have significant hemorrhage associated with their fracture. The question is how well can the FAST identify intraabdominal hemorrhage in these people. The authors' idea is that if the FAST can find intraperitoneal blood, it might help determine who would benefit from REBOA instead of laparotomy.