Physical abuse: bruising and sentinel injuries — formative SAQs

SAQ 1 — Bruise behind the ear in a 3-month-old (10 marks)

A 3-month-old infant is brought to the emergency department with coryza. On examination you notice a 1.5 cm bruise behind the left ear. The caregiver attributes it to the infant wriggling against the bouncy chair. The infant is not yet rolling over independently. ^{[3] [2]}

Questions

1. How do you interpret this bruise, and what is the clinical significance of its location and the infant's mobility? (4 marks) ^{[3] [1]}
2. Outline the investigations you would arrange and why. (3 marks) ^[4]
3. Describe the immediate safeguarding and disposition steps, including the role of mandatory reporting. (3 marks) ^{[4] [2]}

Model answer

Interpretation (4). Bruising is rare in infants who are not yet independently mobile; the foundational work on accidental bruising established that those who do not cruise rarely bruise. A bruise behind the ear is a TEN-4 region (ear) and in the TEN-4 FACES-L rule a single positive feature in a child under four triggers an abuse evaluation. The bouncy-chair mechanism is developmentally implausible for a 3-month-old who is not yet rolling. Treat this as a sentinel injury and a mandatory-reporting trigger. ^{[3] [1] [5]}

Investigations (3). A skeletal survey (dedicated films, not a babygram) because the infant is under two years, with a repeat at about two weeks to reveal occult rib and metaphyseal fractures. A coagulopathy panel (full blood examination and platelets, PT, aPTT, fibrinogen, von Willebrand panel) because bruising is the presenting feature, understanding that a normal result does not exclude abuse. Neuroimaging if any neurological sign or concern for abusive head trauma. ^{[4] [11]}

Safeguarding and disposition (3). Refer to the child-protection and social-work team and the designated doctor for child protection. Make the mandatory report under local statute; do not wait for certainty. Admit to a place of safety while the assessment is completed because the risk of recurrence after a sentinel injury is real regardless of how minor the bruise looks. Screen siblings and other young household contacts for occult injury. Document the mechanism verbatim and the multi-agency plan. ^{[4] [2] [7]}