Explaining fifth disease and protecting the pregnant contact — OSCE

Candidate instructions (8-minute station)

You are the paediatric registrar in the emergency department. A 6-year-old child was sent home from school yesterday with intensely red slapped cheeks and a lacelike rash on the arms and thighs; the diagnosis is erythema infectiosum (fifth disease), caused by parvovirus B19, made on the clinical pattern. The child is afebrile, well and playing. The child's mother, who is twenty weeks pregnant, is in the room and is anxious. [1]

Your tasks are: [1]

1. Explain the diagnosis of fifth disease and what the rash will do over the coming weeks, in plain, reassuring language. [1]
2. Explain the infectivity paradox — that the child is contagious before the rash and is no longer contagious now the rash is visible — and what it means for school and household contacts. [2]
3. Explain why the mother, at twenty weeks pregnant, needs same-day parvovirus B19 serology, what the results will mean, and the surveillance pathway if she is non-immune. [3]
4. Address the parent's anxiety about the unborn baby honestly, including that timely surveillance and intrauterine transfusion give an excellent outcome. [3]

You are not expected to manage the pregnancy yourself — flag that the mother needs same-day review by the maternity and fetal-medicine team because the surveillance window is time-critical. [3]