Intra-oral injury and occult trauma — branching viva

Opening

Examiner: A 5-month-old infant presents with a torn upper labial frenum and a small bruise behind the ear. The carer says the baby fell from a bed. What is your immediate clinical interpretation? [5]

Candidate: A torn labial frenum in a non-mobile infant is a sentinel oral injury — the American Academy of Pediatrics (Kellogg 2005) recognises oral injuries, particularly a torn frenum, as a manifestation of physical abuse that every physician must actively look for. A 5-month-old who does not yet crawl cannot sustain a frenum tear from a fall. The ear bruise is another red flag. I apply the TEN-4 FACES-B bruising rule: the frenum tear is an "F" item and the ear bruise is an "E" item, and any bruise under 4 months is a "4" item (this child is 5 months, but the bruising on the ear and the frenum tear are both positive). This is abuse until excluded, and I proceed to a full safeguarding workup. [5] [7]

Branch A — Recognition and the bruising rule

Examiner: Walk me through the TEN-4 FACES-B rule. [7]

Candidate: TEN-4 FACES-B, validated by Pierce in 2010 and again in 2021 (JAMA Netw Open), is a clinical decision rule for bruising in young children. T is bruising on the torso (chest, abdomen, back, buttocks); E is ear bruising; N is neck bruising; 4 is any bruise in an infant under 4 months. FACES adds Frenulum tear, Angle of jaw, Cheek or corner of mouth, Eyelid, and Sclera or subconjunctival. B is bruising in any non-mobile child. A single positive item indicates a high probability of abuse and warrants the full workup. The Maguire 2005 systematic review underpins this: bruises are rare in pre-mobile infants, and bruising on the torso, ear, or neck is highly suggestive of abuse. [1] [7]

Probe: What is the most powerful single discriminator between inflicted and accidental injury? [3]

Candidate: A history that is inconsistent with the injury or the child's developmental stage. A pre-mobile baby cannot sustain a frenum tear from rolling. A fall from a bed does not explain posterior rib fractures. I document the history verbatim with quotations and note any inconsistencies between informants or across visits — that inconsistency is the strongest single predictor. [3]

Branch B — The occult-trauma screen

Examiner: What is your occult-trauma screen for this child? [2] [3]

Candidate: This is a child under 24 months with suspected abuse, so I perform a skeletal survey — a complete series of approximately 20 views including oblique ribs, as recommended by the AAP Section on Radiology (2009). I repeat it at 2 weeks to reveal occult fractures not visible initially. Because the child has suspected abusive head trauma features, I obtain a CT head acutely and follow with MRI brain and spine when stable. I arrange dilated specialist ophthalmology for retinal haemorrhages. I send AST and ALT — if either is over 80 IU/L, I perform abdominal CT for occult liver injury (Lindberg 2013). I add a coagulation screen and FBC to exclude bleeding diathesis. [2] [9]

Probe: Why repeat the skeletal survey? [2]

Candidate: Because some fractures are not visible initially — occult fractures become apparent as callus forms over approximately 2 weeks. The repeat study improves the yield of occult fractures substantially, especially rib and classic metaphyseal lesions. It is a standard part of the protocol. [2]

Branch C — Abusive head trauma

Examiner: The MRI shows an interhemispheric subdural haematoma and the ophthalmologist reports multilayer retinal haemorrhages too numerous to count. How do you interpret this? [3]

Candidate: This constellation is consistent with abusive head trauma from shaking or impact. The interhemispheric subdural results from tearing of bridging dural veins under acceleration-deceleration; the multilayer, too-numerous-to-count retinal haemorrhages extending to the periphery are characteristic and rarely seen in accidental trauma. The RCPCH 2018 critique affirms that the "triad" (subdural haematoma, retinal haemorrhage, encephalopathy), in context, supports a shaking mechanism, but I interpret it with the full clinical picture — the history, the skeletal survey, and the exclusion of mimics. The PredAHT score (Cowley 2015) can estimate the probability of abuse from six clinical features. [3]

Branch D — Mimics and pitfalls

Examiner: What mimic must you exclude before attributing the frenum tear to abuse? [3]

Candidate: Riga-Fede disease — traumatic ulceration of the ventral tongue or lingual frenum caused by natal or neonatal teeth. It is a developmental, non-inflicted cause of lingual frenum injury in infants. I also exclude a bleeding diaphesis with coagulation and FBC, and I consider osteogenesis imperfecta if there are recurrent or characteristic fractures. Over-diagnosis harms an innocent family; under-diagnosis risks re-injury and death — I weigh both carefully. [1] [3]

Probe: What is the threshold for making a mandatory report? [5]

Candidate: Reasonable suspicion, not certainty. In most jurisdictions a treating doctor has a statutory duty to report suspected child abuse to child protection services at the point of reasonable concern. I do not wait for the full workup to complete before reporting, and I do not discharge the child without a safeguarding plan and a senior-clinician decision. I do not confront or accuse the carer — my role is to document, investigate, and report. [5]

Close

Examiner: One-line take-home. [3]

Candidate: A torn frenum or a sentinel bruise in a non-mobile infant is abuse until excluded — apply TEN-4 FACES-B, screen for occult fractures, retinal haemorrhages, intracranial and abdominal injury, and make the mandatory report before discharge; reasonable suspicion, not certainty, is the threshold. [3] [5] [7]