For the left pleural space, the probe would be located in the posterior axillary line between the fourth and eighth intercostal spaces. Again, rotate the probe toward the back if rib shadows prevent full evaluation.

Scanning the Rectovesicular Space

This space should be evaluated in both the longitudinal and transverse planes. Ideally, the bladder will be full enough to act as an acoustic window to the space behind the bladder. Place the probe above the pubic bone with the probe marker pointing to the patient’s right side, and evaluate for free fluid (an area of hypoecho-genicity) in the anterior vesicouterine space and the posterior rectouterine space (see image 11). Rotate the probe 90 degrees clockwise so that the probe marker points toward the head for evaluation in the longitudinal plane.

Repeating the EFAST

A negative EFAST does not exclude entirely the presence of thoracoabdominal injury. Small amounts of free fluid and small pneumothoraces may not be visible on an initial EFAST. Patients with stable vital signs and a concerning history should be observed for at least 4 hours and have the EFAST repeated. Repeat EFAST should be performed sooner if a patient’s clinical picture is deteriorating and vital signs become unstable.

Conclusion

Pitfalls include:

• Overreliance on ultrasound: Ultrasound cannot evaluate the retroperitoneum and cannot distinguish solid organ injury.
• Delaying transport to operating room: When immediate surgical intervention is clearly indicated (e.g., eviscerating injury), skip the EFAST.
• Failing to scan the inferior pole of the kidney: Free fluid will first accumulate close to the inferior pole of the kidneys.
• Failing to recognize clotted blood: Patients with delayed presentations after thoracoabdominal trauma may not have classic sonographic findings. Clotted blood has variable echogenicity.
• Failure to understand other limitations of EFAST: Morbidly obese patients and those with massive subcutaneous emphysema are challenging to image with ultrasound. Also, EFAST cannot distinguish fluid type and cannot differentiate ascites from blood.

For best results, repeat the ultrasound procedure in patients who deteriorate and before discharge of stable patients. Consider using the low-frequency probe for imaging of the thoracic cavity to decrease the length of time required for this examination.

Always place the patient in the Trendelenburg position to increase the sensitivity of the examination.

In summary, ultrasound is a useful diagnostic tool in the evaluation of patients with thoracoabdominal trauma. The use of EFAST can decrease time to definitive care and length of stay in the emergency department.