Acute gastroenteritis with severe dehydration

Presentation

Good afternoon, sir. I examined Yusuf, an 11-month-old boy with 3 days of frequent watery stools — about ten yesterday — with vomiting for the first day. The stools are copious and watery with no blood or mucus. He has taken very little by mouth and has not passed urine since yesterday morning. He was weaned at 4 months onto pap prepared with stream water, and has not had the rotavirus vaccine. He is lethargic and difficult to rouse, and drinks poorly when offered fluid. His eyes are deeply sunken and he cries without tears; the mouth and tongue are dry. The skin pinch over the abdomen goes back very slowly, over 3 seconds. The anterior fontanelle is depressed. He weighs 7.4 kg, down from 8.2 kg recorded at his last clinic visit 3 weeks ago. The pulse is 168 per minute and thready, the radial pulse barely palpable; capillary refill is 4 seconds; blood pressure 70/40 mmHg; extremities are cold and mottled. The respiratory rate is 56 per minute and deep with no recession or crackles. The abdomen is soft and not distended, with increased bowel sounds, and there is no palpable mass. The temperature is 37.4 °C and there is no rash or neck stiffness. His MUAC is 12.8 cm and there is no oedema. I would like to complete my examination by checking his blood glucose and a malaria test.

Diagnosis

Acute watery gastroenteritis with severe dehydration and hypovolaemic shock, with an estimated fluid deficit of about 10% of body weight — most likely rotavirus, given the age, the season and the absence of blood in the stool.

Differential diagnoses

• Dysentery — Shigella, Campylobacter, invasive E. coli, amoebiasis — blood and mucus in the stool, fever, tenesmus, sometimes convulsions with shigellosis
• Cholera — profuse rice-water stools with rapid, profound dehydration, often in an outbreak; the child is usually over 2 years
• Systemic infection presenting with diarrhoea — malaria, pneumonia, otitis media, urinary tract infection, septicaemia, measles
• Surgical abdomen — intussusception with redcurrant jelly stool and a sausage-shaped mass, or obstruction with bilious vomiting and distension
• Diabetic ketoacidosis — deep sighing breathing with dehydration and weight loss, but polyuria continues despite dehydration
• Persistent diarrhoea or malabsorption — an episode lasting 14 days or more, lactose intolerance, environmental enteric dysfunction
• Haemolytic uraemic syndrome — after bloody diarrhoea, with pallor, oliguria, thrombocytopenia and a rising creatinine
• Antibiotic-associated or C. difficile diarrhoea — recent antibiotic use

Investigations

Severe dehydration is a clinical diagnosis, and treatment starts before any test.

WHO classification of dehydration

Management

Management is led by the paediatric team with nursing, dietetic and public health input. I would explain to the mother that the fluid loss is life-threatening, that we will replace it through a drip and then by mouth, that we will not stop his feeds, and that we will show her how to prevent the next episode.

Non-pharmacological

• Resuscitate immediately — Plan C. Ringer's lactate, or 0.9% saline if unavailable, 100 mL/kg total: for a child aged 12 months to 5 years, 30 mL/kg in the first 30 minutes then 70 mL/kg over 2½ hours; for an infant under 12 months, 30 mL/kg over 1 hour then 70 mL/kg over 5 hours. Yusuf is 11 months, so the infant timing applies. Repeat the first 30 mL/kg if the radial pulse is still weak or absent
• Reassess every 15–30 minutes and reclassify after the full volume; step down to Plan B or A as he improves
• Start ORS 5 mL/kg/hour by mouth as soon as he can drink, usually within 3–4 hours, alongside the drip
• If intravenous access is impossible — nasogastric ORS 20 mL/kg/hour for 6 hours, while arranging transfer or intraosseous access
• Continue feeding. Breastfeeding throughout; resume the usual diet as soon as rehydrated. Do not dilute feeds, do not withhold food, do not switch to a lactose-free formula routinely
• Replace ongoing losses: 50–100 mL of ORS after every loose stool under 2 years, 100–200 mL from 2 years
• Monitor: pulse, perfusion, conscious level, urine output, weight, and the number and volume of stools
• Prevention counselling: exclusive breastfeeding for 6 months, safe water and sanitation, hand washing with soap, food hygiene, rotavirus and measles vaccination, vitamin A supplementation

Pharmacological

• Zinc: 20 mg daily for 10–14 days (10 mg under 6 months), starting as soon as he can take it. It shortens the episode, reduces its severity and reduces recurrence over the following months — one of the highest-value interventions in childhood diarrhoea
• Antibiotics are not indicated for watery diarrhoea. Use them for dysentery (ciprofloxacin or azithromycin for Shigella), suspected cholera (azithromycin or doxycycline as a single dose), amoebiasis and giardiasis (metronidazole), enteric fever, or a child who is septic or immunocompromised
• Correct hypoglycaemia with 10% dextrose 2 mL/kg, and hypokalaemia once he is passing urine
• Antipyretic for fever, and antimalarial treatment if the test is positive
• Ondansetron — a single sublingual dose may allow oral rehydration in a vomiting child where it is available (2 mg for 8–15 kg, 4 mg for 16–30 kg), but most children need only patient, small-volume ORS

Surgical and interventional

• Intraosseous access when a peripheral line cannot be secured in a shocked child
• Surgery only for a complication such as intussusception or a perforation

Complications and follow-up

• Hypovolaemic shock, acute kidney injury and death
• Electrolyte disturbance — hypernatraemic or hyponatraemic dehydration, hypokalaemia with ileus and abdominal distension, metabolic acidosis
• Hypoglycaemia and seizures
• Persistent diarrhoea beyond 14 days, secondary lactose intolerance, and worsening malnutrition — each episode costs weight
• Haemolytic uraemic syndrome after bloody diarrhoea
• Fluid overload and pulmonary oedema from careless rehydration
• Intussusception can both mimic and follow gastroenteritis

Weigh him again before discharge and plot it. Give the mother ORS sachets and zinc to take home with clear instructions, and teach the return signs: passing many stools, repeated vomiting, thirst, sunken eyes, refusing to feed, fever, blood in the stool, or no urine. Review growth in a week and use the visit to complete immunisation and give vitamin A.

Examiner questions

Related resources: Dehydration, fluids and electrolytes, Severe acute malnutrition without oedema (marasmus), Intussusception, Paediatric abdominal examination.

References

• Kliegman RM, St Geme JW, Blum NJ, Tasker RC, Wilson KM, et al., eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia: Elsevier; 2025.
• World Health Organization. Pocket book of hospital care for children: guidelines for the management of common childhood illnesses. 2nd ed. Geneva: WHO; 2013.
• National Institute for Health and Care Excellence. Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management (CG84). London: NICE; 2009.