Association Between Focused Assessment with Sonography in Trauma (FAST) Results, Transfusion, and Injury in Trauma: A Multicenter Retrospective Cohort Study

Objectives The Focused Assessment with Sonography in Trauma (FAST) is central to early trauma resuscitation, but the extent to which FAST findings provide information beyond physiologic and laboratory markers remains incompletely characterized in contemporary practice. Methods We conducted a retrospective multicenter cohort study of adult trauma patients who underwent FAST at 4 Level I trauma centers between 2021 and 2023. The primary outcome was blood transfusion in the emergency department (ED). The secondary outcome was a composite of severe internal injury associated with potential hemorrhage (liver/spleen/kidney injury, hemoperitoneum, pelvic fracture, retroperitoneal hematoma, vascular injury, or hemothorax). Mixed-effects logistic regression was performed. The adjusted odds ratios (aORs) for FAST result were calculated controlling for patient-level variables. Results Among the 2151 trauma patients undergoing FAST, 1792 (83.3%) were documented negative, 335 (15.6%) positive, and 24 (1.1%) indeterminate. Overall, 610 patients (28.4%) were transfused, including 418/1792 (23.3%) FAST-negative, 179/335 (53.4%) FAST-positive, and 13/24 (54.2%) indeterminate ( P < .001). Severe injuries occurred in 675 patients (31.4%), including 445/1792 (24.8%) FAST-negative, 216/335 (64.5%) FAST-positive, and 14/24 (58.3%) indeterminate ( P < .001). In adjusted models, FAST-positive and indeterminate examinations were independently associated with transfusion (positive adjusted odds ratio [aOR] 3.38, 95% CI 2.53 to 4.50; indeterminate aOR 4.11, 95% CI 1.58 to 10.72) and with severe internal injury (positive aOR 4.82, 95% CI 3.66 to 6.35; indeterminate aOR 4.57, 95% CI 1.81 to 11.57). Conclusions Among trauma patients undergoing FAST, positive examinations were independently associated with ED transfusion and severe internal injury. Although limited by small numbers, indeterminate FAST examinations demonstrated similarly elevated risk and should not be considered reassuring; however, these findings should be interpreted cautiously. These findings support the use of FAST as an early risk stratification tool that complements clinical and physiologic assessment.