An algorithm to reduce the incidence of false-negative FAST examinations in patients at high risk for occult injury

Background: The Focused Assessment for the Sonographic Examination of the Trauma patient (FAST) sequentially surveys for the presence or absence of blood in dependent abdominal regions including the right upper quadrant, left upper quadrant, and the pelvis. But it does not readily identify intraparenchymal or retroperitoneal injuries, and a CT scan of the abdomen may be needed to reduce the incidence of missed injuries. We hypothesized that select patients who are considered high risk for occult injuries should undergo a CT scan of the abdomen when the FAST is negative so that occult injuries can be detected. Study Design: An algorithm was prospectively tested for the evaluation of select injured patients over a 3 1/2 -year period. Entrance criteria included adult patients with a blunt mechanism of trauma, a negative FAST examination, and a spine fracture (with or without cord injury), or a pelvic fracture. Trauma team members performed the FAST on patients during the Advanced Trauma Life Support secondary survey. Data recorded included the patient's mechanism and type of injury, the results of the FAST and CT scan examinations, operative or postmortem findings or both, and patient outcomes. Patients with spine injuries were grouped according to spine level and the presence or absence of neurologic deficit. The patients with pelvic fractures were grouped according to the Young and Resnick classification. Results: One hundred two of 1,490 patients (6.8%) who had FAST examinations were entered into this study. Thirty-two patients (30.5%) had spine injuries, with only one false-negative ultrasound result. Seventy patients (68.6%) had pelvic fractures with 13 false-negative ultrasound results: 11 ring (9 from motor vehicle crashes, 2 from pedestrians struck), 1 acetabular, and 1 isolated pelvic fracture. Nine patients underwent non- operative management for solid organ injuries, and 4 patients needed surgery. Conclusions: Based on these preliminary data, we conclude that patients with pelvic ring-type fractures should have CT scans of the abdomen because of the higher yield for occult injuries.