After being struck by a vehicle, what injury could be present in a child even without rib fractures?

The presence of a pulmonary contusion in a child after being struck by a vehicle, even in the absence of rib fractures, can be explained by the mechanism of injury associated with blunt trauma. In children, the thoracic wall is more flexible than in adults, making them less likely to sustain rib fractures from blunt force impact. However, despite the lack of rib fractures, the lungs may still be subjected to intense forces that can lead to bruising of the lung tissue itself—this is what is termed a pulmonary contusion.

A pulmonary contusion occurs when small blood vessels in the lungs are torn, leading to bleeding and edema in the lung parenchyma. This injury can result in symptoms such as difficulty breathing, cough, and decreased oxygen saturation. It is critical to be aware of this potential injury after trauma because it can develop over time and may not be immediately apparent upon initial examination or imaging.

In contrast, other injuries like a flail chest typically require the presence of multiple rib fractures, a symptomatic cardiac contusion generally presents with specific signs and symptoms, and transection of the thoracic aorta represents a devastating injury that usually accompanies more significant trauma, often detectable through imaging modalities or differing clinical signs. Thus, the likelihood of sustaining a