Introduction and Background
Traumatic injuries are among the most common presenting complaint to the emergency department (ED). Oftentimes, these patients will arrive unstable and the clinician must quickly and accurately identify the source of injury. Prior to widespread ultrasound and CT scan availability, diagnostic peritoneal lavage (DPL) was used to identify intraperitoneal hemorrhage. The advantages of DPL were that it could be performed rapidly at the bedside obviating the need for transporting the unstable patient out of the department. DPL is now rarely (if ever) performed as it is invasive, insensitive, and nonspecific with consequent risk for iatrogenic injury. Computed tomography (CT) has the advantage of identifying the location and extent of intraabdominal injury, and can evaluate the retroperitoneum. However, it requires the patient to be transported from the resuscitation area and this is not always possible in an unstable situation. It also exposes the patient to ionizing radiation, is expensive, and is not rapidly repeatable.
The focused assessment with sonography for trauma (FAST) exam, utilized primarily by emergency physicians and trauma surgeons, has become a widely accepted screening tool for the blunt trauma patient. Ultrasound for pneumothorax has also been incorporated as part of the extended FAST (E-FAST). The E-FAST exam can be performed quickly at the bedside, is noninvasive, and allows for serial imaging of the injured patient without exposing them to ionizing radiation. Studies have shown that the FAST exam can be learned rapidly by clinicians and is sensitive and specific for intraabdominal and intrathoracic free fluid and pneumothorax. Sonography is particularly helpful in penetrating thoracic trauma. Ultrasound can also be used to evaluate a patient’s volume status, confirm endotracheal tube placement, and identify fractures. Ultrasound can be used to guide procedures and assess the progress of resuscitation efforts. The E-FAST exam is at the interface between the physical examination and diagnostic imaging, and in the hands of a trained clinician provides a real-time view of patient anatomy, may be used to corroborate clinical findings, and narrows the differential diagnosis.
The Ultrasound Approach to the Acute Trauma Patient
The ultrasound approach to the acute trauma patient depends on the mechanism of injury and the presenting complaint(s). An algorithmic approach to the trauma patient is outlined in Fig. 24-1.
In any significant blunt trauma, a full E-FAST examination should be performed at the bedside to assess the extent of injuries. The sonographer should begin by evaluating the patient for the presence of free fluid in the abdomen or thorax. This is accomplished by obtaining both right (RUQ) and left upper quadrant (LUQ) views and the pelvis looking for intraperitoneal fluid, indicating a hemoperitoneum. The technique to obtain adequate images is described fully in Chap. 9. In the evaluation of the RUQ and LUQ, a thorough look above the diaphragm should also be performed, looking for pleural fluid, indicating a hemothorax. In the young female patient, the pelvic view should include interrogation of the uterus for obvious pregnancy, which may be visualized prior to hCG results. Ultrasound is also very helpful in the pregnant trauma patient, where radiation from CT is preferably avoided.