Original Scientific Articles
An algorithm to reduce the incidence of false-negative FAST∗ examinations in patients at high risk for occult injury1

Presented at the American College of Surgeons 84th Annual Clinical Congress, Orlando, FL, October 1998.
https://doi.org/10.1016/S1072-7515(99)00121-0Get rights and content

Abstract

Background: The Focused Assessment for the Sonographic Examination of the Trauma patient (FAST) sequentially surveys for the presence or absence of blood in dependent abdominal regions including the right upper quadrant, left upper quadrant, and the pelvis. But it does not readily identify intraparenchymal or retroperitoneal injuries, and a CT scan of the abdomen may be needed to reduce the incidence of missed injuries. We hypothesized that select patients who are considered high risk for occult injuries should undergo a CT scan of the abdomen when the FAST is negative so that occult injuries can be detected.

Study Design: An algorithm was prospectively tested for the evaluation of select injured patients over a 312-year period. Entrance criteria included adult patients with a blunt mechanism of trauma, a negative FAST examination, and a spine fracture (with or without cord injury), or a pelvic fracture. Trauma team members performed the FAST on patients during the Advanced Trauma Life Support secondary survey. Data recorded included the patient’s mechanism and type of injury, the results of the FAST and CT scan examinations, operative or postmortem findings or both, and patient outcomes. Patients with spine injuries were grouped according to spine level and the presence or absence of neurologic deficit. The patients with pelvic fractures were grouped according to the Young and Resnick classification.

Results: One hundred two of 1,490 patients (6.8%) who had FAST examinations were entered into this study. Thirty-two patients (30.5%) had spine injuries, with only one false-negative ultrasound result. Seventy patients (68.6%) had pelvic fractures with 13 false-negative ultrasound results: 11 ring (9 from motor vehicle crashes, 2 from pedestrians struck), 1 acetabular, and 1 isolated pelvic fracture. Nine patients underwent nonoperative management for solid organ injuries, and 4 patients needed surgery.

Conclusions: Based on these preliminary data, we conclude that patients with pelvic ring-type fractures should have CT scans of the abdomen because of the higher yield for occult injuries.

Section snippets

Methods

An algorithm was prospectively used for evaluating select injured patients (nonconsecutive sample) who were admitted to our Level I trauma center during a 312-year period. To be entered into the study, adult patients had to have a blunt mechanism of trauma, a negative FAST examination, and either a spine fracture with or without cord injury, or a pelvic fracture. Although several types of injuries are associated with high energy impact and the potential for occult injury, only those patients

Results

During a 312-year period, 1,490 patients with blunt mechanisms of injury had FAST examinations by surgeon-sonographers. One hundred two (6.8%) of those patients entered this study, the majority (86%) of whom were men. The mean age and the mean Injury Severity Score (ISS) of the study population were 34 ± 0.5 years and 36 ± 12 years, respectively. (Of note, the sensitivity and specificity of the other 1,389 patients were 79.8% and 79.1%, respectively).

Discussion

As a rapid and accurate method to detect hemoperitoneum, the FAST examination is suitable for the evaluation of most patients with blunt mechanisms of injury.1, 2, 3, 4, 9, 10, 11, 12, 13, 14, 15, 16 Its inability to detect consistently multiple injuries as previously mentioned has been reported as the reason for false-negative results in several studies,1, 3, 12, 17, 19 and an additional CT scan of the abdomen is occasionally recommended. Data that further define the indications for a CT scan

Invited commentary

David B Hoyt San Diego, CA

I’d like to congratulate Dr Ballard and his colleagues for their leading work in the development of ultrasound for the evaluation of abdominal trauma, and for their ongoing refinement how best to use this important advance for taking care of trauma patients.

The current study hypothesizes that energy transfer associated with spinal fractures and pelvic fractures might be associated with a higher incidence of “missed injuries” when evaluated by ultrasound and should

Reply

Grace S Rozycki, md, rdms, facs

Atlanta, GA

The authors would like to express our appreciation to Dr Hoyt for his insightful discussion of our manuscript.

Although we cannot give an exact figure for the “miss rate” for small bowel, diaphragm, and bladder injuries for patients who were evaluated by CT scan, we do recommend the use of several modalities if the index of suspicion is particularly high for these injuries. For example, the patient whose CT scan of the abdomen has fluid but no solid

Acknowledgements

The authors would like to express their appreciation to the residents of the Department of Surgery from Emory University School of Medicine, and to Christa Gardner for her valuable assistance with the preparation of this manuscript.

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    Focused Assessment for the Sonographic Examination of the Trauma patient.

    1

    No competing interests declared.

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