Background:
Early and accurate diagnosis of any internal injury in cases of multiple trauma is crucial in decreasing morbidity and mortality. Focused Assessment with Sonography for Trauma (FAST) is a quick, non-invasive imaging method widely used in emergency departments. The current research aimed to assess the diagnostic accuracy of FAST with regards to hemodynamic, clinical, and paraclinical features, and also to analyze the characteristics and the clinical relevance of the false-negative FAST results.
Methods:
This cross-sectional research comprised 300 cases of multiple trauma patients admitted to Kosar Hospital, Sanandaj, during 2021 and 2023 years. Pneumothorax and intraabdominal free fluid results of FAST were compared with results of contrast-enhanced computed tomography (CT) scans. The vital signs and laboratory values were assessed, and diagnostic performance indicators were measured (including sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]).
Results:
In the presence of positive FAST test for pneumothorax, 96.9% were confirmed by CT (false-positive rate: 3.1%). Nevertheless, FAST missed 21.3% of pneumothoraxes. For detection of free fluid, 97% agreement between FAST and CT was established, with a false-negative rate of 20.1%. Patients with a positive FAST test had significantly lower blood pressure, elevated heart rate, and low oxygen saturation. In contrast, patients with a false-negative FAST test exhibited rather stable hemodynamic and laboratory parameters. Mortality rate reached 36.7%, and there was significantly higher mortality among patients with positive FAST results.
Conclusion:
FAST is an effective and fast diagnostic method, which is highly specific. Nevertheless, the relatively high rate of false-negative results remains the major limitation of this test, especially particularly in hemodynamically stable patients. Consequently, the absence of fluid on FAST scan warrants careful interpretation and further imaging in case of doubt.