Clinical reasoning, problem representation and differential diagnosis — branching viva

Opening stem

A 6-week-old returns 18 hours after discharge with “likely viral illness.” The caregiver says the baby is more lethargic and not themselves. Observations are only mildly abnormal. [5] [6]

Station 1 — Representation (must pass)

Examiner prompt: Give your one-sentence problem representation. [1] [2]

Expected: Age; return visit after viral label; tempo of worsening lethargy; mild snapshot observations; caregiver concern; high residual threat posture for serious infection, cardiac or metabolic disease; need for senior rewrite rather than simple reassurance. [1] [2] [5]

Fail if: Retells the whole history without compression; ignores return context; closes with “just viral.” [1] [6]

Station 2 — Differential and traps

Examiner prompt: Rank your differential and name the main cognitive trap if you simply re-endorse the discharge label. [3] [4]

Expected: Threat-first list (serious bacterial infection/sepsis, cardiac, metabolic, respiratory failure, context-dependent safeguarding). Trap: premature closure or diagnostic momentum from the previous label; possible anchoring on mild observations. Counter with diagnostic pause and residual-risk statement. [3] [4] [6]

Branch A — Complex child

New stem: Same shift, a technology-dependent school-age child is “not their normal.” [7]

Expected: Representation includes personal baseline, devices, emergency plan and change from usual. Keep device failure and intercurrent illness open. Do not attribute all findings to the known diagnosis. [7] [9]

Branch B — Safeguarding curiosity

New stem: A toddler limp has an injury story that does not match developmental stage. [10]

Expected: Hold non-accidental injury on the differential; document exact words; treat medically; follow local pathway; no public accusation. Name confirmation bias and search-satisfying as risks. [10] [4]

Station 3 — Handover under uncertainty

Examiner prompt: Hand over to the night registrar. [8]

Expected: Provisional working diagnosis; residual risks; actions and response; next discriminating step and timing; caregiver concern; criteria for senior escalation. Not “stable viral, no concerns.” [8] [3]

Closing communication

Examiner prompt: Explain uncertainty to the infant’s caregiver in two or three sentences. [3] [5]

Expected: Most likely problem, what you are still protecting against, what you will do now, what to watch for, how to get help. No false certainty. [3] [5]