Background: Focused assessment with sonography for trauma (FAST) as a screening tool in the evaluation of blunt abdominal trauma will lead to underdiagnosis of abdominal injuries and may have an impact on treatment and outcome in trauma patients.
Methods: From October 2001 to June 2002, a protocol for evaluating hemodynamically stable trauma patients with suspected blunt abdominal injury (BAI) admitted to our institution was implemented using FAST examination as a screening tool for BAI and computed tomographic (CT) scanning of the abdomen and pelvis as a confirmatory test. At the completion of the secondary survey, patients underwent a four-view FAST examination (Sonosite, Bothell, WA) followed within 1 hour by an abdominal/pelvic CT scan. The FAST examination was considered positive if it demonstrated evidence of free intra-abdominal fluid. Clinical, laboratory, and imaging results were recorded at admission, and FAST examination results were compared with CT scan findings, noting the discordance.
Results: Patients with suspicion for BAI were evaluated according to protocol (n = 372). Thirteen cases were excluded for inadequate FAST examinations, leaving 359 patients for analysis. There were 313 true-negative FAST examinations, 16 true-positives, 22 false-negatives, and 8 false-positives. Using CT scanning as the confirmatory test for hemoperitoneum, FAST examination had a sensitivity of 42%, a specificity of 98%, a positive predictive value of 67%, a negative predictive value of 93%, and an accuracy of 92%; chi analysis showed significant discordance between FAST examination and CT scan (5.85%, < 0.001). Six patients with false-negative FAST examinations required laparotomy for intra-abdominal injuries; 16 patients required admission for nonoperative management of injury. Of the 313 true-negative FAST examinations, 19 patients were noted to have intra-abdominal injuries without hemoperitoneum and 11 patients were noted to have retroperitoneal injuries.
Conclusion: Use of FAST examination as a screening tool for BAI in the hemodynamically stable trauma patient results in underdiagnosis of intra-abdominal injury. This may have an impact on treatment and outcome in trauma patients. Hemodynamically stable patients with suspected BAI should undergo routine CT scanning.