Predictive value of a false-negative focused abdominal sonography for trauma (FAST) result in patients with confirmed traumatic abdominal injury

OBJECTIVE: To investigate if patients with confirmed traumatic abdominal injury and a false-negative focused abdominal sonography for trauma (FAST) examination have a more favorable prognosis than those with a true-positive FAST. METHODS: This study included 97 consecutive patients with confirmed traumatic abdominal injury (based on computed tomography [CT] and/or surgical findings) who underwent FAST. RESULTS: FAST was false-negative in 40 patients (41.2%) and true-positive in 57 patients (58.8%). Twenty-two patients (22.7%) had an unfavorable outcome (defined as the need for an interventional radiologic procedure, laparotomy, or death due to abdominal injury). Univariately, a false-negative FAST (odds ratio [OR] 0.24; p = 0.017) and a higher systolic blood pressure (OR, 0.97 per mmHg increase; p = 0.034) were significantly associated with a favorable outcome, whereas contrast extravasation on CT (OR, 7.17; p = 0.001) and shock index classification (OR, 1.89 for each higher class; p = 0.046) were significantly associated with an unfavorable outcome. Multivariately, only contrast extravasation on CT remained significantly associated with an unfavorable outcome (OR, 4.64; p = 0.016). When excluding contrast extravasation on CT from multivariate analysis, only a false-negative FAST result was predictive of a favorable outcome (OR, 0.28; p = 0.038). CONCLUSION: Trauma patients with confirmed abdominal injury and a false-negative FAST have a better outcome than those with a positive FAST. FAST may be valuable for risk stratification and prognostication in patients with a high suspicion of abdominal injury when CT has not been performed yet or when CT is not available.