Azygos vein laceration due to blunt trauma.

The azygos vein ascends along the thoracic spine through the mediastinum and drains into the superior vena cava at the level of the fourth thoracic vertebra. Fracture-dislocation of the mid-thoracic spine, as a result of blunt thoracic trauma, can tear the azygos vein. Four such fatal cases (three motor vehicle accidents and one fall) were studied, only one of which was recognized prior to death. The vein can also be torn, in the absence of skeletal injuries, by horizontal acceleration/deceleration forces. The pathologist must consider azygos vein laceration as a possible cause of either hemothorax or hemomediastinum or both in a victim of a blunt chest trauma, if that individual had persistent hypotension during the few hours before death and no identifiable source of hemorrhage can be found postmortem in sites such as the heart, great vessels, lung, and chest wall. A fracture-dislocation of the thoracic spine may not necessarily be present. Azygos vein laceration seems to be an uncommon cause of hemothorax and hemomediastinum; however, this injury is probably more frequent than is implied by the few cases described in the medical literature.