In closed soft tissue injuries, the surface of the skin is not broken. Although soft tissue injuries can and do occur on any part of the body, they are common on extremities.
Two common closed soft tissue injuries are contusions and hematomas.
Contusions (bruises) are usually caused by a blow from a blunt instrument (from a stick, for example) or by the body impacting with an object (falling to the ground, for example). The site of the injury normally turns “black and blue.” The discoloration (ecchymosis) is caused by blood from the injury which is trapped and, with time, changes color. The site of the injury often swells due to the presence of blood and fluid leaking from the injured tissue cells (edema). Pain usually accompanies the injury.
A hematoma (blood tumor) is a localized collection of blood, often clotted, in the damaged tissues due to a break in the wall of a blood vessel. A hematoma is more serious than a contusion. Normal hematomas can contain more than 50 milliliters of blood and can often be palpated (felt with the fingers or hand). Severe hematomas, such as the internal bleeding associated with a fractured femur or pelvis, can contain a liter or more of blood and result in hypovolemic shock.