Written by Alex Chen
CT scan of the abdomen/pelvis had 100% sensitivity (95%CI 92.5-100) for detecting intra-abdominal injury in trauma patients with abdominal seat belt sign (ASBS). Both abrasions or ecchymoses over the seat belt area were associated with increased risk of intra-abdominal injury.
Why does this matter?
If you work at a trauma center, you are bound to see motor vehicle accidents coming in. One of the things we look for on our secondary survey is a seat belt sign which can indicate a higher risk of intra-abdominal injury. These patients are often observed or admitted due to the potential for missed injuries on initial work-up. In these times of worsening hospital crowding, anything that can allow us to safely discharge patients from ED is helpful.
“When in doubt, scan it.” -some wise ED attending
This was a retrospective case series conducted at a Level I trauma center in which they identified 425 ED patients with confirmed ASBS through chart review. 415 of 425 (97.7%) of these patients received a CT scan, and they found that the overall incidence of intra-abdominal injury was 38.1% in this cohort, with 13.6% undergoing exploratory laparotomy. Initial CT scan had a 100% sensitivity (95%CI 92.5-100) for detecting intra-abdominal injury. No patients in this sample that had an initial negative CT went on to have a positive finding on repeat CT. While the sensitivity looks great, just be cautious; the lower end of the confidence interval is 92.5%, and this was a retrospective case series which could have missed patients who had more subtle exam findings that excluded them from this study. Finally, if the patient’s abdomen remains extremely tender, even with a negative CT, don’t send them home.
Patients with Abrasion or Ecchymosis Seat Belt Sign Have High Risk for Abdominal Injury, but Initial Computed Tomography is 100% Sensitive. J Emerg Med. 2020 Aug 18:S0736-4679(20)30660-0. doi: 10.1016/j.jemermed.2020.06.057. Online ahead of print.
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