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Seatbelt Sign as a Predictor of Intra-abdominal Injury

May 10, 2024

Written by Laura Murphy

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Presence of a seatbelt sign (SBS) was associated with a higher likelihood of intra-abdominal injury and need for surgical intervention.

Buckle up for the details
This systematic review and meta-analysis of ten observational studies from 1997-2022 (6 retrospective, 4 prospective) included 3,050 patients and demonstrated pooled prevalence of intra-abdominal injury among patients with SBS of 42% (95%CI 28%-58%, I2=96%); 46.9% of 1,937 patients with SBS were diagnosed with intra-abdominal injury compared to 19.2% of 1113 patients without SBS. The presence of SBS was associated with significantly increased odds of intra-abdominal injury (OR 3.62, 95%CI 1.12-1.16, P=0.03, I2=89%) and increased likelihood of surgical intervention (OR 7.34, 95%CI 2.03-26.54, P<0.001, I2=29%).

There was significant heterogeneity, likely in part due to the large time period spanned by the meta-analysis. For measurement of intra-abdominal injury, there was variation across studies in mode of detection. Most studies used CT imaging, but some earlier studies used diagnostic peritoneal lavage (which is no longer widely used) and others didn’t specify. There was no mention of ultrasound in this study, which is widely used today and can be important in decision-making for unstable patients. Furthermore, recent technological advances in CT scanners with thinner slices lead to higher sensitivity for diagnosis of intra-abdominal injury. There have also been technological advancements in seatbelts (e.g. pretensioners and load limiters), which likely has affected incidence of intra-abdominal injuries.

With this in mind, it is hard to say if the value pooled prevalence derived from a wide time period is truly accurate, and further studies are needed since some of these important technological advances. Nevertheless, the results overall suggest that the presence of SBS after MVC is associated with statistically significant increase in odds of intra-abdominal injury as well as in odds of surgical intervention. Further studies are likely needed to better characterize prevalence of injury in the current day and age.

How will this change my practice?
With that said, I will continue to have a very low threshold for abdomen/pelvis CT imaging in trauma patients presenting with SBS. Newer generations of CT scanners have a better sensitivity for intra-abdominal injury, so need for observation of patients with negative CTs may decrease. Nevertheless, I will continue to counsel patients about possibility of delayed presentation in patients that go home.

Prevalence of intra-abdominal injury among patients with seatbelt signs, a systematic review and meta-analysis. Am J Emerg Med. 2024 Feb;76:199-206. doi: 10.1016/j.ajem.2023.11.058. Epub 2023 Dec 3. PMID: 38086186.

What are your thoughts?