I have probably reviewed more than 9,000 ultrasound scans during my years as an ultrasound director. I evaluate all of the FAST exams that are performed for our trauma patients, which means hundreds of scans a year at our busy trauma center. I have seen many interesting cases, many great diagnoses, and several significant mistakes in that time. Some of these mistakes resulted from a lack of careful and thorough scanning, but most of them were a result of misinterpretation of the images on screen. Beginning this month, I am opening my FAST files to share these cases with you.
An 8-year-old child presented after a high-speed motor vehicle crash. The EP was told the child was improperly restrained in a lap belt. The child was alert and interactive, the vital signs were stable, and no head trauma or loss of consciousness was reported. The child was crying but cooperative. The primary survey did not reveal any immediate life threats, but the secondary survey revealed an abrasion to the anterior abdominal wall that was consistent with the seat belt sign.
Significant abdominal tenderness was present, and a FAST exam was done at the bedside as part of the initial trauma evaluation. After some confusion regarding difficulty in obtaining images of the upper quadrants, the exam was read initially as negative. The child was then taken for a CT scan, where a large amount of complex fluid was found, along with free air. The child decompensated while in CT, and was taken emergently to the operating room, where a duodenal perforation was found and repaired.
A review of the images in this case showed several abnormalities pointing to the diagnosis of hollow viscus injury. The views of the pelvis are the most striking. (Images 1 and 2; videos available at http://bit.ly/VideosSound.) The bladder can be seen as a rounded collection of anechoic fluid. Just superior to the bladder, a complex collection can be seen with what appears to be particulate matter within it. This can be seen in both the transverse and sagittal views. With this knowledge in hand, a closer review of the right upper quadrant reveals an abnormality in the hepatorenal interface. (Image 3; video available at http://bit.ly/VideosSound.) The liver and kidney should abut each other with little between them, particularly in thin pediatric patients. In this case, a hypoechoic, irregular area consistent with gastric contents and air is noted.
Putting together the facts in this case, an abdominal injury was suspected initially. Hollow viscus injury is a significant concern in children, particularly with this mechanism. The FAST exam demonstrated the evidence of a hollow viscus rupture, but it was not correctly interpreted. Most examiners are seeking an anechoic (black) fluid collection, and may miss even large collections that don't meet these criteria. Keep an open mind when looking for signs of injury. It might look different from what you expect.