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]}