Approach to rash in infants and children — formative SAQs

SAQ 1 (10 marks, 15 minutes)

Stem: A 3-year-old is brought to the emergency department with fever, irritability and a rash that has spread over the last four hours. On examination the child is drowsy, tachycardic, and has several lesions on the limbs that do not fade under glass-slide pressure. Outline your structured approach, immediate management, and the reasoning that underpins it. ^[7]

Model answer (marker scaffold)

Immediate recognition and threat assessment (3 marks):

• State that an unwell, febrile child with a non-blanching (purpuric) rash is presumed to have invasive bacterial sepsis, classically meningococcaemia, until proven otherwise.
• Apply a morphology-first, distribution-aware approach: morphology is purpura (extravasated blood); distribution is spreading and systemic; the unwell child makes this an emergency regardless of the named diagnosis.
• State the principle: resuscitate and treat the threat first; do not delay antibiotics for investigations or for the rash to "look typical". ^[7]

Immediate management (4 marks):

• ABCDE: oxygen, airway and breathing support; establish intravenous or intraosseous access.
• Take blood cultures and a meningococcal PCR, but give a parenteral third-generation cephalosporin (e.g. ceftriaxone or cefotaxime) immediately per local paediatric sepsis protocol - exact dose by weight and age.
• Manage shock with fluid boluses; reassess after every intervention; involve senior paediatric staff and retrieval early.
• Lumbar puncture only if clinically safe and indicated, and never before antibiotics in a shocked child. ^[7]

Reasoning and safety-net (3 marks):

• Explain why blanching is the key bedside discriminator: purpura does not blanch because blood is outside the vessel.
• Name the diagnostic trap of early meningococcaemia being nonspecific before purpura evolves.
• State disposition: admit to a paediatric centre with PICU involvement as required; safety-net the family and notify public health once the diagnosis is confirmed. ^[7]