The azygos vein runs under the pleura along the right aspect of the thoracic spine. At the fourth thoracic vertebra, the azygos vein arches over the pulmonary hilum to join the superior vena cava (see Fig. 36 and ref. 323).
Tearing of the azygos vein from blunt trauma is uncommon but must be considered in the differential diagnosis of an evolving hemothorax or hemomediastinum (323-327). Most cases have occurred in motor vehicle crashes (326). A survival interval of several hours, during which there is persistent hypotension despite vigorous resuscitative efforts and surgical repair of other bleeding sources, is characteristic (323,326). There can be an associated midthoracic spine fracture that can directly tear the vein, but most lacerations occur either close to the superior vena cava-azygos vein junction or along the azygos vein arch (Fig. 36; refs. 323 and 326). Shearing from deceleration is a proposed mechanism of injury (323,326,328).
If a right hemothorax is observed postmortem, the azygos vein must be inspected in situ after blood is removed from the pleural cavity. If this inspection is not done prior
to removal of the heart and lungs, then this dissection will cut through the site of vein laceration.
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