Acute gastroenteritis and infectious diarrhoea — structured clinical encounter

Structured encounter testing the approach to an 18-month-old with two days of watery diarrhoea and vomiting who is mildly-to-moderately dehydrated: the clinical grading of dehydration, the exclusion of surgical and metabolic mimics, the design of oral rehydration therapy with low-osmolarity solution and nasogastric back-up, the adjuncts of ondansetron and zinc with early feeding, the recognition of severe dehydration needing intravenous resuscitation, and the safety-netting and disposition conversation with the family.

structured clinical encounter2 min readVerification in progress

Prompt

An 18-month-old boy has two days of frequent watery, non-bloody diarrhoea and vomiting with reduced wet nappies. He is restless and irritable with sunken eyes, dry mucosa, a slow skin pinch and prolonged capillary refill, but is alert with warm peripheries. You are the paediatric registrar working through assessment, rehydration, adjuncts, escalation and counselling.

Station 1 — assessment and grading

Asked for my first impression, I explain that a toddler with two days of watery, non-bloody diarrhoea and vomiting has acute gastroenteritis, and that my priority is to grade his dehydration. His sunken eyes, dry mucosa, slow skin pinch and prolonged capillary refill in an alert child with warm peripheries place him in the some, or mild-to-moderate, dehydration group rather than shock. I would weigh him and compare with a recent well weight if available. [3] [4]

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References7Show ledger

[1]Guarino A; Ashkenazi S; Gendrel D; et al European Society for Pediatric Gastroenterology, Hepatology, and Nutrition/European Society for Pediatric Infectious Diseases evidence-based guidelines for the management of acute gastroenteritis in children in Europe: update 2014. J Pediatr Gastroenterol Nutr, 2014.PMID 24739189
[3]Steiner MJ; DeWalt DA; Byerley JS Is this child dehydrated? JAMA, 2004.PMID 15187057
[4]Bailey B; Gravel J; Goldman RD; et al External validation of the clinical dehydration scale for children with acute gastroenteritis. Acad Emerg Med, 2010.PMID 20624137
[8]Lifschitz C; Kozhevnikov O; Oesterling C; et al Acute gastroenteritis-changes to the recommended original oral rehydrating salts: a review. Front Pediatr, 2023.PMID 38192370
[5]Lazzerini M; Wanzira H Oral zinc for treating diarrhoea in children. Cochrane Database Syst Rev, 2016.PMID 27996088
[13]Freedman SB; Williamson-Urquhart S; Plint AC; et al Multidose Ondansetron after Emergency Visits in Children with Gastroenteritis. N Engl J Med, 2025.PMID 40673584
[14]Sumner M; Xie J; Williamson-Urquhart S; et al Persistent Vomiting Among Children With Acute Gastroenteritis: A Secondary Analysis of a Randomized Clinical Trial. JAMA Netw Open, 2026.PMID 42090154