Blunt Abdominal Trauma: Clinical Value of Negative Screening US Scans

Abstract

Ultrasonography is the primary screening examination for blunt abdominal trauma in a number of centers in Europe and Asia and in select centers in the United States. The advantages of ultrasonography are that it is nonionizing and portable and can be performed during ongoing resuscitation without interference. However, the use of screening ultrasonography for detection of blunt abdominal trauma is controversial. The sensitivity of ultrasonography for detection of abdominal injury ranges from 63% to 99% in published series and compares favorably with that for computed tomography (CT). The concern is that injuries may be missed in patients with negative findings on ultrasonography; thus, the clinical value of negative screening ultrasonography is unclear. The clinical and surgical outcomes in patients with blunt abdominal trauma and negative findings on screening ultrasonography were assessed. A database of 4,000 patients who underwent screening ultrasonography for suspected blunt trauma at a Level I trauma center was used to retrospectively identify 3,679 patients with negative findings on ultrasonography. The outcome in these patients was determined by a retrospective review of the trauma registry and all radiologic, surgical, and autopsy reports. All imaging studies and medical charts in patients with false-negative findings at screening ultrasonography were also reviewed. Among the 3,679 patients with negative findings at screening ultrasonography, 99.9% had no injuries (true-negative findings). The differences in true-negative rates as a function of year or time of day were not significant. Among the 3,641 patients with true-negative findings, 93.7% required no additional tests, and 6.4% underwent CT or other tests. The percentage of patients who underwent additional tests was significantly higher in the first year of the study (19.2%) than in subsequent years. Thirty-eight patients had false-negative ultrasonography findings for abdominal injury. The injuries that were missed in 24 patients were nonsurgical, and those in 14 patients were surgical. Overall, 65 injuries were missed. The 6 most common injuries were retroperitoneal hematoma (n=13) and injuries in the spleen (n=10), liver (n=9), kidney (n=8), adrenal gland (n=8), and small bowel (n=7). No or trace hemoperitoneum was found in 25 of the 38 patients with false-negative ultrasonography findings for abdominal injury. The mean diagnostic delay until recognition of missed injury was 16.8 hours. The missed injury was identified within 12 hours in 19 (50%) of 38 patients and within 24 hours in 24 (70%) of 34 patients. Negative findings on ultrasonography in combination with negative clinical observations are virtually exclusive of abdominal injury in patients who are admitted and observed for at least 12 to 24 hours.