Acute Gastroenteritis in Children
Acute gastroenteritis is an inflammation of the stomach and intestines that leads to vomiting and diarrhoea. It’s a very common illness in children and is typically self-limiting. The primary clinical challenge is to assess the child’s hydration status and rule out more serious differential diagnoses. UK guidance from the National Institute for Health and Care Excellence (NICE) focuses on a systematic approach to assessment and management based on the degree of dehydration.
Aetiology and Differential Diagnosis
Viruses: The most common cause is viral, with Rotavirus and Norovirus being the most prevalent.
Bacteria: Bacterial causes, though less frequent, are often more severe and include Salmonella, Shigella, Campylobacter, and E. coli O157.
Other: Parasites like Giardia can also cause gastroenteritis.
Differential Diagnosis
It’s crucial to consider other causes of vomiting and diarrhoea, especially if there are red flags.
Surgical causes: Intussusception, acute appendicitis, or bowel obstruction.
Systemic illness: Sepsis, diabetic ketoacidosis (DKA), or a urinary tract infection (UTI).
Neurological: Raised intracranial pressure (ICP) from a head injury or meningitis.
Toxins: Accidental poisoning.
Clinical Assessment
History
A detailed history is vital to assess the severity of the illness and the risk of dehydration.
Symptoms: Ask about the frequency and nature of vomiting (e.g., is it bilious?) and diarrhoea (e.g., is there blood or mucus?).
Fluid Intake: Quantify fluid intake over the last 24 hours. Ask about the last time the child passed urine, as this is a key indicator of hydration.
Risk Factors: Identify children at high risk of dehydration:
Infants, especially those under 6 months.
Prematurity or low birth weight.
Children with comorbidities (e.g., chronic kidney disease).
Examination
Overall Appearance: Look for signs of shock or lethargy.
Hydration Status: A key focus of the exam is assessing the degree of dehydration.
No Dehydration: Child is well, has moist mucous membranes, and is urinating normally.
Mild to Moderate Dehydration: Child may have a slightly reduced level of consciousness, decreased urine output, and reduced skin turgor. They may have a dry mouth and no tears when crying.
Severe Dehydration: The child is lethargic or unconscious, has sunken eyes, absent tears, and a prolonged capillary refill time (>2 seconds). This is a medical emergency.
Systemic Exam: Perform a full systemic exam to rule out a differential diagnosis, particularly looking for signs of sepsis, meningitis, or a surgical abdomen.
Management
Management is based on the degree of dehydration. The primary goal is rehydration and maintenance.
No or Mild Dehydration
Oral Rehydration: Discharge the child home with clear advice for parents.
Continue Feeds: Advise parents to continue the child’s normal diet and offer frequent small sips of fluids.
Oral Rehydration Solution (ORS): If the child is not tolerating their usual fluids, ORS can be used.
Moderate Dehydration
Hospital-Based Oral Rehydration: Admit the child for an oral rehydration challenge.
ORS: Give ORS at a dose of 50 ml/kg over 4 hours.
Monitoring: Monitor the child closely for signs of improvement. If they are unable to tolerate ORS orally, it can be given via a nasogastric tube (NGT).
Severe Dehydration or Shock
Emergency Management: This is a medical emergency. Follow the ABCDE approach.
Intravenous (IV) Fluid Resuscitation: Administer an IV fluid bolus of 20 ml/kg of 0.9% sodium chloride over 10 to 15 minutes. This can be repeated if the child’s condition does not improve.
Fluid Management: Once the child is stabilised, start maintenance IV fluids and a correction plan to replace the estimated fluid deficit over the next 24 hours.
Investigations
Blood tests: Not routinely needed for mild to moderate dehydration. For severe dehydration, check U&Es to assess for electrolyte abnormalities.
Stool cultures: Only needed for severe diarrhoea, prolonged illness, or if a bacterial cause is suspected.
Urine: In infants under 3 months, a urine analysis should be considered to rule out a UTI.
Management of Acute Gastroenteritis in Children
The management of acute gastroenteritis in children is primarily supportive and aims to prevent or treat dehydration. The key is a step-by-step approach based on the child’s hydration status, and the choice of fluid is critical.
1. Assessment and Classification
First, assess the degree of dehydration:
No Dehydration: Child is well, has moist mucous membranes, and is urinating normally.
Clinical Dehydration: Child has signs of dehydration such as reduced skin turgor, sunken eyes, a dry mouth, or reduced urine output.
Clinical Shock: Child is lethargic or unresponsive, has a prolonged capillary refill time, and is peripherally shut down. This is a medical emergency.
2. Oral Rehydration Therapy (ORT)
This is the first-line treatment for children with no dehydration or clinical dehydration.
Choice of Fluid: Use a low-osmolarity oral rehydration solution (ORS) (e.g., Dioralyte). ORS is superior to water, juice, or sugary drinks because it contains a balanced mix of sugar and electrolytes that helps the intestines absorb fluid more efficiently.
Dose:
No Dehydration: Give ORS after each loose stool or episode of vomiting.
Clinical Dehydration: Give a dose of 50 ml/kg of ORS over 4 hours.
Feeding: Continue with the child’s normal diet or formula alongside ORS. Breastfeeding should not be stopped.
3. Intravenous (IV) Fluid Therapy
IV fluids are reserved for children with clinical shock or those with clinical dehydration who fail ORT.
Fluid Choice: The recommended fluid for resuscitation is a 20 ml/kg bolus of 0.9% sodium chloride (normal saline). This can be repeated if the child’s condition does not improve.
Maintenance and Deficit: After resuscitation, IV fluids should be continued to cover maintenance needs and correct the remaining fluid deficit over 24 hours. The fluid used for this purpose is typically 0.9% sodium chloride with 5% glucose.
4. Specific Management Points
Anti-emetics: Anti-emetic drugs are not recommended in children with gastroenteritis.
Anti-diarrhoeals: Anti-diarrhoeal medications are also not recommended.
Blood Tests: Routine blood tests are not needed for mild to moderate dehydration. A blood gas should be taken in cases of suspected shock or severe dehydration to check for metabolic acidosis and electrolyte imbalances.
Antibiotics: Antibiotics are not routinely used as most cases are viral. They are only considered in specific bacterial infections or for severe disease in immunocompromised children.
5. Discharge and Safety-Netting
Children with no or mild dehydration can be managed at home. Parents should be given clear safety-netting advice on when to return to the hospital, including signs of worsening dehydration (e.g., lethargy, reduced urine output) or the presence of new red flags.