Internal injuries can be difficult to detect. Internal bleeding can result from any source of bleeding inside your body, can quickly turn fatal if not detected soon after the accident, can be the result of abdominal trauma following an accident, or the result of a ruptured spleen. A punctured lung can occur when the ribs are broken or a sharp object punctures the lung. When the brain is struck hard enough, a brain bleed can occur, leading to brain damage or a stroke.