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Bruising characteristics from unintentional injuries in children: the ‘green flag’ study
  1. Mary Clyde Pierce
  1. Correspondence to Dr Mary Clyde Pierce, Department of Pediatrics, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, Illinois, USA; MPierce{at}

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Bruising in young children is probably the most overlooked or underappreciated injury prior to a child being severely injured or killed at the hands of their caregiver/s. In fact, 28%–64% of children who sustained subsequent severe physical abuse injuries had prior ‘sentinel’ bruising that was overlooked or dismissed as insignificant by a professional providing care for the child.1 2 This harm-causing oversight is likely driven by several factors: (1) bruising in and of itself rarely needs an intervention or treatment, and in medicine, we focus on findings (signs and symptoms) that need our immediate attention or add to our understanding of the patient’s condition. Thus, we overlook what does not register as important. (2) Bruising is common, ubiquitous and, for the most part, an inconsequential finding on active toddlers and older children, and (3) even if the bruise is noticed, the clinician may not feel comfortable concluding whether a bruise is or is not likely to occur from any one stated cause. In the spirit of being ‘non-accusatory with families’, the clinician is more likely to give the family the ‘benefit of the doubt’ and not make judgements about the bruising and injury ‘plausibility’.

Common trauma mechanisms that result in bruising include falls from standing or sitting, running/falling into an object (such as the edge of a coffee table), short falls of around 1 m (3.28 feet) (eg, fall off of furniture including a couch, bed, chair, swing, table, changing table and cabinets), stair falls, falls/drops from caregivers’ arms, falls with the caregivers and falls off playground equipment. Other common injuries include being struck by an object (such as a toy) or being hit by another child. However, in many instances of bruising from abuse, the child’s caregiver provides a fabricated history of trauma, similar to the above-listed examples, to conceal the abusive act.

Are there key bruising distributions or characteristics that help clinicians distinguish between true and fabricated histories of injury?

Several studies have identified key findings in bruising characteristics (‘red flags’) between abused and unintentionally injured children, with a predominant focus on improved recognition of the abused child.3–5 An enhanced understanding of detailed bruising characteristics associated with true accidental injury occurrences across different ages would add significantly to the evidence base required for clinicians to better assess injury plausibility and identify false or fabricated trauma histories. Knowing what bruises occur in accidental injury allows identification of false or fabricated trauma histories. This can lead to better differentiation of abusive versus accidental trauma at the individual patient level.

In the linked article titled ‘Childhood bruising distribution observed from eight mechanisms of unintentional injury’, authors Hibberd and colleagues6 provide new, detailed evidence of bruising characteristics in context to the child’s age and developmental capabilities. They analysed injuries resulting from eight recognised trauma mechanisms adapted from the International Classification of External Causes of Injury. Summarised results are based on 693 bruises from 559 incidents in children 13 years of age and younger. This prospective cross-sectional study is one of the first to add such detailed information on bruising characteristics in relation to specific injury events across different development stages. Strengths of this study include a high level of rigour to exclude potential abuse cases that might confound results, and the use of two different populations of patients (emergency department and community clinics) to improve generalisability. This well-done study establishes an evidence base to access injury plausibly regarding bruise characteristics and injury history. In addition, previously published red flags regarding bruising characteristics from physical abuse are further validated by the very absence or extremely low frequency of these ‘red flag’ findings in this cohort of patients with unintentional injuries.

This study on bruising from eight specific unintentional injuries provides several take away points.6 Among the 372 children examined who had bruising, all but seven of these children were mobile, no one had more than five bruises from a single incident and the majority had only one bruise. Key, simple-to-apply findings from this study are synthesised in table 1.

Table 1

Bruise counts occurring from a single incident

The take home points regarding bruise counts are that three or more bruises occurring from a single incident is uncommon, and when present, one of the following mechanisms is expected: stair fall involving multiple stairs, sports injury or motor vehicle crash. More than five bruises from any stated cause brings into question the plausibility and veracity of the history for children who are otherwise healthy.

Hibbard et al found that bruises most often occurred to the front of the body over a bony area such as the forehead or shin. When two or more bruises did occur, they were in the same body region or on the same side of the body. Interestingly, there were only two incidents where bruising occurred to both the front and the back of the body from the same event. Patterned bruising was uncommon as was petechial or clustered bruising. Other researchers report similar results on developmental stage of the child, bruise count and appearance and distribution but none with the detail of this prospectively conducted study.5 7–9

Table 2 highlights key ‘green flags’ of bruising characteristics to aid with assessing injury plausibility as identified in the study by Hibberd et al.6 Table 3 highlights potential red flags of abuse and reports on the low or no occurrences in this study of bruising from unintentional injury. References of similar findings from other studies are included.

Table 2

Green flags: common bruise findings from unintentional injury to aid with assessing injury plausibility—Hibberd et al 6 study results with other supporting studies referenced

Table 3

Red flags: rare or absent bruise occurrences resulting from a single injury incident*

In summary, the study by Hibberd et al provides a new level of evidence and improved accuracy for assessing injury plausibility and bruising.6 Key identified factors in relation to the stated cause of injury includes the age of the child and developmental stage, the number of bruises and location of bruises on the body and whether the bruise is patterned or petechial. Knowing what bruise findings are consistent from a given mechanism of injury allows for improved recognition of when inconsistencies are present. Improved accuracy in injury assessments brings multifaceted benefits for children and families. Specifically, this knowledge has the potential to benefit the abused child by improving medical recognition of when a child’s injuries from a stated cause are well out of the realm of plausible and the subsequently required legal evidence to support that opinion. Conversely, improved accuracy for assessing injuries in children also helps innocent families seeking care for their accidentally injured child by improving medical recognition of when a child’s injuries fit well within expected outcomes for a specific mechanism of injury. Further work expanding on the evidence from this study has the potential to substantially improve the clinician’s ability to differentiate abuse from accidental trauma. Such expansion might include prospective studies of all injury types occurring from the specified injury mechanisms regardless of bruise occurrence and enrolling a significantly larger sample size from many different emergency departments from diverse settings.



  • Handling editor Martin Ward Platt

  • Competing interests None declared.

  • Patient consent Not applicable.

  • Provenance and peer review Commissioned; internally peer reviewed.

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