Physical abuse: bruising and sentinel injuries — branching viva

Stem

You are in a mixed acute paediatric setting. The examiner will move you through recognition, investigation, differential and safeguarding. [4] [2]

Branch 1 — Recognition

Examiner: A 3-month-old is seen for coryza. You find a 1.5 cm bruise behind the ear. The family blames the bouncy chair. What is your interpretation? [3]

Strong answer: Bruising is rare in infants who are not yet independently mobile — the foundational work showed those who do not cruise rarely bruise. A bruise behind the ear is a TEN-4 region, and in the TEN-4 FACES-L rule one positive feature in a child under four triggers an abuse evaluation. The mechanism is developmentally implausible. This is a sentinel injury and a reporting trigger. [3] [1] [5]

Branch 2 — Investigation

Examiner: What investigations will you arrange, and why? [4]

Strong answer: Skeletal survey as a dedicated film set because the infant is under two, with a repeat at about two weeks to reveal occult rib and metaphyseal fractures. Coagulopathy panel (platelets, PT, aPTT, fibrinogen, von Willebrand) because bruising is the presenting feature, with the explicit understanding that a normal result does not exclude abuse. Neuroimaging if any neurological concern. [4] [11]

Examiner: The coagulation screen is normal. Does that close the case? [11]

Strong answer: No. A normal screen excludes some bleeding disorders but not rare ones and not the pattern. A bleeding disorder and abuse can coexist. Continue the full work-up in parallel with safeguarding. [11] [4]

Branch 3 — The differential

Examiner: The family mentions coin rubbing and says the child is clumsy. How does that change things? [4]

Strong answer: Cultural-practice marks such as coin rubbing are typically symmetric, on expected sites, and openly explained; document them respectfully and do not conflate with abuse. But a claim of cultural practice does not override a genuine high-specificity pattern elsewhere, and "clumsiness" must be tested against developmental plausibility rather than accepted at face value. [4]

Branch 4 — Sentinel injury and prevention

Examiner: Why does this infant matter beyond today? [2]

Strong answer: This is a sentinel injury — a minor inflicted injury in a non-mobile infant. Sentinel injuries are prior missed opportunities; children who later present with abusive head trauma often had a documented sentinel injury that was explained away. Acting now prevents recurrence. [2] [7]

Branch 5 — Safeguarding

Examiner: Close the encounter. [4]

Strong answer: Child-protection and social-work referral, designated doctor for child protection, mandatory report under local statute, admit to a place of safety, screen siblings, document mechanism verbatim and the multi-agency plan. Do not confront the caregiver in the corridor; the clinician recognises and refers, the multi-agency team investigates. [4] [2]

Examiner extras

• Torn frenum in a pre-mobile infant is a sentinel injury. [9]
• Patterned bruising is inflicted by definition. [4]
• Do not date bruises by colour. [4]
• Always repeat the skeletal survey at about two weeks. [4]