Pelvic fractures are often associated with severe hemorrhage due to the extensive blood supply to the region.

http://en.wikipedia.org/wiki/Pelvic_fracture

Various muscles play important roles in pelvic stability.Because of the forces involved, pelvic fractures frequently involve injury to organs contained within the bony pelvis. In addition, trauma to extra-pelvic organs is common. Pelvic fractures are often associated with severe hemorrhage due to the extensive blood supply to the region.