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A caveat to the performance of pericardial ultrasound in patients with penetrating cardiac wounds.

BACKGROUND
The pericardial window in a focused assessment with sonography for trauma (FAST) examination is highly accurate for detecting hemopericardium and, therefore, associated cardiac injury. A series of patients with false-negative pericardial ultrasound examinations, who were subsequently diagnosed with cardiac lacerations after presenting with stab wounds, are described.


METHODS
All patients with a normal pericardial ultrasound examination, despite subsequent diagnosis of a cardiac injury, are described (2005-2008).


RESULTS
Five patients with stab wounds to the precodium displayed initial and repeatedly normal pericardial windows on a FAST examination. Each patient was eventually diagnosed with a penetrating cardiac injury and concurrent laceration of their pericardial sac. This combination of injuries allowed decompression of blood from the cardiac injury into the thoracic cavity and, therefore, prevented accumulation of a hemopericardium.


CONCLUSIONS
The pericardial component of the FAST examination is commonly used for patients who present with penetrating wounds to the precordium. In cases of concurrent lacerations of the pericardial sac, pericardial ultrasound may not detect a cardiac injury because of associated decompression into the thoracic cavity.