From the RSNA refresher courses: focused abdominal US for trauma.

Focused abdominal ultrasonography (US) has been introduced in Europe as a method to evaluate blunt abdominal trauma. The main focus of the examination is detection of free fluid in the abdomen secondary to injury of the abdominal organs. The examination takes only a few minutes to perform. In the authors' experience, trauma patients in unstable condition and in whom significant free fluid is detected are immediately taken to the operating room for surgical exploration without undergoing computed tomographic (CT) correlation. The authors have also used US to identify the specific site of organ injury. Injuries to solid organs such as the liver, spleen, and kidney that are identified with US usually appear heterogeneous or hyperechoic. A hematoma surrounding the injured organ may appear echogenic or hypoechoic. However, pitfalls of focused abdominal US for trauma include failure to show contained solid-organ injuries; injuries to the diaphragm, pancreas, and adrenal gland; and some bowel injuries. Thus, negative findings at US do not exclude an intraperitoneal injury, and close clinical observation or CT is warranted.