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Shiga toxin-associated haemolytic uraemic syndrome — MRCEM SBA MCQ

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HardPaediatric emergenciesShiga toxin-associated haemolytic uraemic syndromeMRCEM SBA

A 4-year-old girl presents after six days of diarrhoea, which became bloody three days ago. She visited a farm shortly before becoming unwell. Today she has passed very little urine. She is alert, warm and well perfused, with a capillary refill time of 2 seconds. Her blood pressure is 124/78 mmHg; she has periorbital oedema and weighs 1 kg more than at a clinic visit last week. Haemoglobin is 78 g/L, platelets 48 × 10⁹/L and creatinine 162 µmol/L. A blood film shows schistocytes. Potassium is 4.8 mmol/L, and there is no respiratory distress. A stool sample has been sent for Shiga toxin-producing *Escherichia coli* testing, but the result is pending. What is the most appropriate immediate management plan?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Limit IV fluid to insensible losses plus urine output, seek urgent paediatric nephrology advice, and arrange high-dependency care.

The bloody-diarrhoea prodrome and farm exposure suggest Shiga toxin-producing *E. coli*. Schistocytes and anaemia indicate microangiopathic haemolysis; thrombocytopenia and acute kidney injury complete the clinical picture of haemolytic uraemic syndrome (HUS). The pending stool result must not delay escalation. Oliguria, weight gain and oedema indicate a risk of fluid overload, while her preserved perfusion provides no indication for an immediate resuscitation bolus. Once resuscitation needs have been excluded, IV fluid should be reduced to insensible losses plus urine output, with close fluid-balance monitoring, urgent paediatric nephrology and critical-care involvement, and high-dependency care pending specialist disposition. ([gov.uk](https://www.gov.uk/guidance/shiga-toxin-producing-escherichia-coli-stec-diagnosis-and-notification)) **B** applies the more generous hydration approach used for some children with bloody diarrhoea *before* HUS develops; it is inappropriate once oliguria and overload are present. **C** would be reasonable if she were shocked or clinically hypovolaemic, but neither is evident. **D** is tempting because the diarrhoea is bloody, but antibiotics are not routinely used to treat suspected STEC infection alone; a separate indication such as suspected sepsis would change that decision. **E** targets acquired thrombotic thrombocytopenic purpura, for which plasma exchange is used, rather than this characteristic diarrhoea-associated HUS presentation. Suspected HUS should also be notified to the local health protection team without waiting for microbiological confirmation. ([doclibrary-rcht.cornwall.nhs.uk](https://doclibrary-rcht.cornwall.nhs.uk/DocumentsLibrary/RoyalCornwallHospitalsTrust/Clinical/Paediatrics/Gastroenterology/PaediatricBloodyDiarrhoeaHaemolyticUraemicSyndromeHUSClinicalGuideline.pdf))

Reference: Paediatric Bloody Diarrhoea/Haemolytic Uraemic Syndrome (HUS) Clinical Guideline, version 2.0 (September 2025) — https://doclibrary-rcht.cornwall.nhs.uk/DocumentsLibrary/RoyalCornwallHospitalsTrust/Clinical/Paediatrics/Gastroenterology/PaediatricBloodyDiarrhoeaHaemolyticUraemicSyndromeHUSClinicalGuideline.pdf Shiga toxin-producing Escherichia coli (STEC): diagnosis and notification (4 January 2024) — https://www.gov.uk/guidance/shiga-toxin-producing-escherichia-coli-stec-diagnosis-and-notification Plasma exchange for patients with thrombotic thrombocytopenic purpura (TTP) (2024) — https://www.cuh.nhs.uk/patient-information/plasma-exchange-for-patients-with-thrombotic-thrombocytopenic-purpura-ttp/