Imaging description

During the focused assessment with sonography for trauma (FAST) scan, the epicardial fat pad can be mistaken for hemopericardium or a pericardial effusion [1]. This is more often seen in obese patients and can appear sonographically anechoic (Figure 43.1). To avoid this pitfall, Blaivas et al. suggest using a modified sub-xiphoid view [1]. In this technique the probe is angled perpendicular to the skin, visualizing the inferior vena cava (IVC) entering the right atrium, which allows visualization of the right side of the heart next to the diaphragm. Any amount of pericardial fluid that is not loculated will be seen in this location. Also, in this view the IVC should collapse at least 50% with a sudden inspiration. Collapse of less than 50% indicates increased central pressure, possibly due to tamponade. Imaging the IVC as it enters the heart can be performed quickly and does not add significant time to the FAST examination.

If differentiating between a hemopericardium and an epicardial fat pad remains difficult despite this technique, and the patient is stable, further imaging with computed tomography provides rapid differentiation (Figure 43.2).