Intra-oral injury and occult trauma — formative SAQs

SAQ 1 (10 marks)

A 4-month-old infant presents with a 2-day history of poor feeding and irritability. The mother says the baby " bumped the mouth on the cot rail" two days ago. On examination, the upper labial frenum is torn and bruised, and there is a small bruise behind the left ear. The baby does not roll, sit, or crawl. There are no other external injuries, and the child is haemodynamically stable with a normal neurological examination. [3] [5]

1. State three features of this presentation that indicate this is a sentinel injury requiring a safeguarding workup, and name the bruising clinical decision rule that applies. (3) [7] [8]
2. Outline the occult-trauma screen you would perform, with the specific threshold that triggers abdominal imaging. (4) [9] [14]
3. Describe the immediate safeguarding actions you must take before considering discharge. (3) [3] [5]

Model answer — SAQ 1

(1) Sentinel-injury features and the bruising rule (3). Three features: the child is non-mobile (does not roll, sit, or crawl) — any bruise or oral injury in a pre-mobile infant is highly suggestive of abuse (Maguire 2005); the torn upper labial frenum is a classic inflicted oral sign (Kellogg 2005) and an "F" item in the TEN-4 FACES-B rule; the bruise behind the left ear is an "E" (ear) item. The rule is TEN-4 FACES-B (Pierce 2010, validated 2021): bruise on Torso, Ear, or Neck; any bruise under 4 months; Frenulum tear; Angle of jaw, Cheek, Eyelid, Sclera; Bruising in any non-mobile child. [1] [7] [8]

(2) Occult-trauma screen (4). Skeletal survey — a complete series of approximately 20 views including oblique ribs, for all children under 24 months with suspected abuse (AAP Section on Radiology 2009), with a repeat at 2 weeks to reveal fractures not initially visible. CT head acutely (this infant is under 6 months with an abusive injury and irritability), followed by MRI brain and spine when stable for injury dating and diffuse axonal injury. Dilated specialist ophthalmology for multilayer retinal haemorrhages. AST and ALT — if either is over 80 IU/L, perform abdominal CT for occult liver injury (Lindberg 2013); add lipase and urinalysis. Coagulation and FBC to exclude bleeding diathesis. [2] [9] [14]

(3) Immediate safeguarding actions (3). Do not discharge the child without a safeguarding plan and a senior-clinician decision — the child must not be returned to an unsafe environment while the workup is pending. Make a mandatory report to child protection — the threshold is reasonable suspicion, not certainty. Notify a senior clinician and the local child-protection team, and engage social work. Do not confront or accuse the carer; document the history verbatim with quotations, photo-document injuries on a body map, and follow institutional forensic protocol. [3] [5]

SAQ 2 (10 marks)

A 10-month-old infant is brought in after an unwitnessed fall. The carer's account changes between interviews. Physical examination reveals a torn frenum, a single bruise on the abdomen, and the child is mildly lethargic. Skeletal survey shows three posterior-lateral rib fractures and a classic metaphyseal lesion of the distal femur. [2] [3]

1. Explain why the posterior-lateral rib fracture and the classic metaphyseal lesion are highly specific for inflicted injury. (3) [2]
2. Describe the neuroimaging and ophthalmology assessment you would perform and the characteristic retinal finding of abusive head trauma. (4) [3]
3. Name two mimics you must exclude before attributing the injuries to abuse, and the relevant screening tests. (3) [1] [3]

Model answer — SAQ 2

(1) Specificity of the fractures (3). The Kemp 2008 systematic review (BMJ) established that posterior-lateral rib fractures are produced by compression that levers the rib head against the transverse process — an mechanism that requires substantial squeezing force, not a fall. Classic metaphyseal lesions (corner or bucket-handle fractures) result from shearing of the immature trabeculae at the zone of provisional calcification from pulling, twisting, or shaking — again inconsistent with a simple fall. Both fracture types are highly specific for inflicted injury, particularly in infants. Multiple fractures of different ages further strengthen the inference. [2]

(2) Neuroimaging and ophthalmology (4). The lethargy and changing history mandate neuroimaging for suspected abusive head trauma. CT head is the acute test for subdural haematoma and acute haemorrhage; MRI brain and spine (once stable) is obtained for injury dating, diffuse axonal injury, and subtle or chronic subdural collections. Dilated specialist ophthalmology is mandatory — the characteristic finding is multilayer, too-numerous-to-count retinal haemorrhages extending to the periphery, a pattern rarely seen in accidental trauma. The PredAHT score (Cowley 2015) may help estimate the probability of abuse from clinical features. [3]

(3) Mimics to exclude (3). First, a bleeding diaphesis — ITP, haemophilia, or Von Willebrand disease — can cause bruising and must be excluded with a coagulation screen and FBC before attributing bruising to abuse. Second, osteogenesis imperfecta (or other bone fragility syndromes) can cause recurrent fractures; screen with a careful history for blue sclera, dentinogenesis imperfecta, family history, and characteristic radiographs. A recognised oral mimic is Riga-Fede disease — traumatic ulceration of the lingual frenum from natal or neonatal teeth — which is developmental and not inflicted. [1] [3]