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Three Part Question

In [children involved in motor vehicle trauma] is the [seat belt sign] predictive of [significant intra-abdominal injury]?

Clinical Scenario

A 9-year-old boy presents to the Emergency Department (ED) following a motor vehicle collision. He was a restrained rear seated passenger involved in a head on crash at approximately 45 mph. His physical examination is unremarkable, except for the presence of bruising on the lower abdomen in the distribution of his lap belt, consistent with a ‘seat belt sign,’ (SBS). The boy otherwise looks well. You wonder whether there is evidence to help you decide to discharge the patient, pursue additional imaging, or admit the child for observation/further intervention.

Search Strategy

Ovid MEDLINE 1948 to November Week 2 2011
Embase via NHS Evidence 1980—date of searching 21 November 2011
The Cochrane Library November 2011
Medline:[exp abdominal injuries] AND [seat belt sign.mp]. Limit to English language and all child (0–18 years).

Embase: [exp abdominal injuries AND *SEATBELT/] OR [seat and belt and sign ti.ab.]

Cochrane: MeSH descriptor Seat Belts explode all trees.

Search Outcome

Fifty-one papers were identified of which three were relevant to the clinical question and of sufficient quality for inclusion

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Sokolove et al, 2005, United States	Children 16 years of age and younger with blunt trauma at risk for intra-abdominal injury who presented to the ED following a motor vehicle collision over a two year time period. 390 children of whom 46 had SBS.	Prospective Observational Study	Relative Risk (RR) of SBS for gastrointestinal tract injury	12.8 (5.3, 31) P=0.001	Evaluation bias was mentioned as a weakness in the paper, as patients with abnormal physical findings, including SBS, were more likely to undergo radiographic or surgical evaluation. The sample size was small in regard to patients with seatbelt sign but no abdominal pain, limiting recommendations for clinical evaluation in this group.
			RR For Pancreatic injury	22.4 (2.4, 211) P=0.006
			RR For Solid Organ injury	0.9 (0.3, 2.4) P<1.00
			RR For Intra-Abdominal injury	2.9 (1.7, 5.0) P=0.001
Chidester et al, 2009, United States	All Pediatric patients involved in an MVC, requiring trauma team activation from 2005 to 2006, divided into cohorts based on whether a seatbelt sign was documented on physical exam. 390 children of whom 46 had SBS.	Retrospective Review	Relative Risk for intra-abdominal injury	1.7 (0.96-2.69) P=0.078	The study is limited in that it is a retrospective, single institution study. The study was unable to obtain information whether children without SBS were restrained passengers, which may explain why children without SBS were more severely injured. There was a small number of children in the SBS cohort, limiting statistical significance of SBS as an indicator of abdominal injury
			Sensitivity & Specificity of SBS for identifying abdominal injiury	25% and 85%
Paris et al, 2010, Canada	Children admitted to a Canadian tertiary pediatric trauma care center with abdominal wall bruising following MVC over a 10 year time period 53 children	Retrospective Chart Review	Pulse rate>120 as predictor for Intestinal Peforation	OR=9.75 P=0.048	The study is limited in that it is a retrospective single institution study. The study does not directly compare patients with SBS to those without SBS. 28% of patients with SBS underwent evaluation for lumbar fracture by physical exam alone.
			Free Intra abdominal Fluids as predictor for Intestinal Peforation	OR=none P<=0.001
			Associated Lumbar Fractures as predictor for Intestinal Peforation	OR=4.77 P=0.008

Comment(s)

With the introduction of seat belts in automobiles, passenger mortality in motor vehicle collisions has significantly decreased due to changes in injury patterns. The injury pattern noted with seatbelt use has been called the ‘seat belt syndrome,’ consisting of abdominal wall bruising (known as a ‘seatbelt sign’ or SBS), lumbar spine fractures, and intra abdominal injury. Intra abdominal injury can be difficult to diagnose upon initial presentation, and outcomes improve as injuries are identified earlier. The SBS is a frequent clinical finding in children after motor vehicle collision and the studies included in this analysis seek to establish the predictive value of the SBS in paediatric patients as a clinical indicator for further diagnostic evaluation. Two of the three studies compared patients with and without SBS, using those without as controls, and the third study involved only patients with SBS, dividing these patients between those who underwent operation, and those who did not.

Clinical Bottom Line

The seatbelt sign appears to be associated with an increased risk of intra-abdominal injuries, especially gastrointestinal and pancreatic injuries. Patients with SBS along with tachycardia, lumbar fracture, or free intra-abdominal fluid require continued close observation and may need operative intervention.

References

1. Sokolove PE, Kuppermann N, Holmes JF. Association between the “seat belt sign” and intra-abdominal injury in children with blunt torso trauma. Academic Emergency Medicine 2005; 12(9):808-13.
2. Chidester S, Rana A, Lowell W et al. Is the “Seat Belt Sign” associated with serious abdominal injuries in pediatric trauma? Journal of Trauma: Injury Infection & Critical Care 2009; 67(1 Suppl):S34-6.
3. Paris C, Brindamour M, Ouimet A et al. Predictive Indicators for bowel Injury in pediatric patients who present with a positive seat belt sign after motor vehicle collision. Journal of Pediatric Surgery 2010; 45(5):921-4.