Gastroenteritis Summary

Dehydration Assessment

  • Green: No clinical dehydration
  • Amber: Clinical dehydration
  • Red: Shock - urgent treatment

Rehydration Therapy

  • ORT: First-line for dehydration
  • IV fluids: For shock or failed ORT
  • Hypernatraemia: Slow correction

Antibiotic Indications

  • Septicaemia suspected
  • Extra-intestinal spread
  • Specific pathogens
  • Immunocompromised

Fluid Calculations

  • Deficit: 50-100 ml/kg
  • Maintenance: Holliday-Segar
  • Shock: 10-20 ml/kg bolus

Investigations

  • Stool MC&S if indicated
  • U&E if IV fluids needed
  • Blood gas if shock
  • Avoid routine blood tests

Paediatric Gastroenteritis

Overview

Gastroenteritis should be suspected if there is a sudden change in stool consistency to loose or watery stools, and/or a sudden onset of vomiting. If you suspect gastroenteritis, ask about recent contact with someone with acute diarrhoea and/or vomiting and exposure to a known source of enteric infection (possibly contaminated water or food) and recent travel abroad.


Mild/No Dehydration

Clinical Dehydration

Shock

Differential Diagnosis

Non-enteric Infection

  • Meningitis
  • Septicaemia
  • Urinary tract infection
  • Pneumonia

Non-infective GI Conditions

  • Inflammatory bowel disease
  • Coeliac disease
  • Malabsorption
  • Constipation with overflow diarrhoea

Acute Surgical Conditions

  • Appendicitis
  • Volvulus
  • Intussusception
  • Pyloric stenosis

Other

  • Antibiotic associated diarrhoea (including C. diff)

Risk Factors for Dehydration

Assessment of Dehydration

No Clinically Detectable Dehydration Clinical Dehydration Shock
Appears well Appears to be unwell or deteriorating /
Alert and responsive Altered responsiveness (irritable, lethargic) Decreased level of consciousness
Normal urine output Decreased urine output /
Skin colour unchanged Skin colour unchanged Pale or mottled skin
Warm extremities Warm extremities Cold extremities
Eyes not sunken Sunken eyes /
Moist mucous membranes Dry mucous membranes /
Normal heart rate Tachycardia Tachycardia
Normal breathing pattern Tachypnoea Tachypnoea
Normal peripheral pulses Normal peripheral pulses Weak peripheral pulses
Normal capillary refill time Normal capillary refill time Prolonged capillary refill time
Normal skin turgor Reduced skin turgor /
Normal blood pressure Normal blood pressure Hypotension

Red flag symptoms and signs indicating children at increased risk of progression to shock

Hypernatraemic Dehydration (Na+ > 150 mmol/L)

Suspected if:

  • Jittery movements
  • Increased muscle tone
  • Hyperreflexia
  • Convulsions
  • Drowsiness or coma

Investigations

Stool Microbiology

Perform if:

  • Septicaemia suspected
  • Blood/mucus in stool
  • Child is immunocompromised

Consider if:

  • Recent travel abroad
  • Diarrhoea not improved by day 7
  • Diagnostic uncertainty

Other Investigations

  • Avoid routine blood biochemistry
  • Measure U&Es and glucose if IV fluids needed or hypernatraemia suspected
  • Blood gas if shock suspected/confirmed
  • Blood cultures if starting antibiotics
  • Specialist advice for STEC infection (monitor for HUS)

Antibiotic Therapy

Do not routinely give antibiotics to children with gastroenteritis.

Give antibiotics if:

  • Suspected/confirmed septicaemia
  • Extra-intestinal spread of bacterial infection
  • <6 months with salmonella gastroenteritis
  • Malnourished/immunocompromised with salmonella
  • C. difficile, giardiasis, shigellosis, amoebiasis or cholera

For children recently abroad, seek specialist advice.

Management

No Clinical Dehydration

  • Manage at home with advice
  • Continue breastfeeding/milk feeds
  • Encourage fluids (avoid fruit juices/carbonated drinks)
  • Offer ORS if increased risk of dehydration
  • Advise on hygiene and exclusion from school (48h after last episode)
  • No swimming for 2 weeks after diarrhoea
  • Expected duration:
    • Vomiting: 1-2 days (usually stops within 3 days)
    • Diarrhoea: 5-7 days (usually stops within 2 weeks)

Clinical Dehydration

  • Oral rehydration therapy (continue breastfeeding):
    • Low osmolarity ORS
    • 50 ml/kg over 4 hours plus maintenance
    • Small frequent amounts
    • NG tube if unable to drink/vomiting persistently
  • IV fluids if:
    • Shock suspected/confirmed
    • Deterioration despite ORT
    • Persistent vomiting of ORS

Fluid Deficit Calculation

  • Mild dehydration: 50 ml/kg deficit
  • Moderate-severe dehydration: 100 ml/kg deficit
  • Replace over: 4-24 hours depending on severity
  • Monitor: Clinical status, urine output, electrolytes

IV Fluid Therapy for Shock

  • 10 ml/kg 0.9% NaCl rapid IV infusion
  • Repeat 10 ml/kg if still shocked after first bolus
  • Consider PICU referral if still shocked after second bolus
  • When shock resolves, start rehydration with IV fluids

IV Fluid Therapy for Rehydration

  • Isotonic solution (0.9% NaCl or 0.9% NaCl with 5% glucose)
  • Previously shocked: 100 ml/kg deficit + maintenance
  • Not shocked: 50 ml/kg deficit + maintenance
  • Monitor electrolytes/blood glucose regularly
  • Introduce ORT early if tolerated

Hypernatraemic Dehydration

  • Seek urgent expert advice
  • Isotonic solution (0.9% NaCl or 0.9% NaCl with 5% glucose)
  • Replace deficit slowly (typically over 48h)
  • Reduce Na+ at <0.5 mmol/L/hour

After Rehydration

  • Encourage breastfeeding/milk feeds
  • Consider 5 ml/kg ORS after each large watery stool in high-risk children
  • Restart ORT if dehydration recurs

Holliday-Segar Formula (Maintenance Fluids)

  • First 10 kg: 100 ml/kg/day (4 ml/kg/hr)
  • Next 10-20 kg: 50 ml/kg/day (2 ml/kg/hr)
  • Each kg >20 kg: 20 ml/kg/day (1 ml/kg/hr)