What type of injury would most likely lead to internal hemorrhage?

A fractured rib is most likely to lead to internal hemorrhage due to the anatomical structures surrounding the ribcage. When ribs are fractured, there is a significant risk of damaging the blood vessels and organs housed within the thoracic cavity, such as the lungs and major vessels like the aorta and pulmonary arteries. This can result in bleeding, either from the direct injury to these vessels or as a consequence of associated injuries such as a hemothorax (blood in the pleural space) or lacerated lung tissue.

In contrast, a stable pelvic fracture, while it can potentially lead to bleeding, typically does not produce the same immediate risk of severe hemorrhage as rib fractures because the pelvis is relatively stable, and the injury does not always compromise major blood vessels. An open skull fracture, although severe, has its own distinct concerns primarily related to infection and brain injury, rather than immediate internal bleeding. Finally, a closed femur fracture can certainly lead to complications, but it is more likely associated with bleeding into the soft tissue surrounding the fracture site rather than direct internal hemorrhage into a body cavity.

Thus, the nature of rib injuries makes them particularly notorious for causing significant internal bleeding.