Childhood diarrhoea is most often caused by infection but much less often is due to other causes, e.g. malabsorption, endocrine abnormalities, hormone-secreting tumours, pancreatic and liver dysfunction. Acute-onset diarrhoea is usually self-limiting but may have a protracted course. The most common complication of acute diarrhoea is dehydration. Non-infectious causes of diarrhoea may have other systemic signs and symptoms and should be considered in all cases, especially if an acute-onset diarrhoea fails to resolve within 14 days or if the condition recurs.

Also see article on Gastroenteritis in Children.

Acute diarrhoea

Epidemiology

Each year in the UK, gastroenteritis leads to hospital admission in 7/1000 children under the age of 5 years.

Differential diagnosis

Infectious diarrhoea in children is mostly viral, worrying features that should suggest a diagnosis other than acute, viral gastroenteritis include:

• A generally unwell child - out of proportion to the level of dehydration.
• Abdominal pain with tenderness and guarding (possible surgical problem, e.g. appendicitis or intussusception).
• Shock, pallor, jaundice, poor urinary output.
• Bilious vomiting.
• Blood in stool (possible intussusception or haemolytic uraemic syndrome).

Causes of acute diarrhoea

• Viral infection: mainly rotavirus but others include echo and enteroviruses.
• Bacterial infection: suggested by high pyrexia and bloody diarrhoea. Common bacterial pathogens include Shigella spp., Salmonella spp. and Campylobacter spp.
• Protozoal infection: chronic infections might suggest protozoans, for example Giardia lamblia.
• Systemic infection: e.g. urinary tract infection, pneumonia, otitis media, meningitis, septicaemia.
• Antibiotic associated and rarely pseudomembranous colitis.
• Dietary: food allergy or intolerance (lactose, cow's milk protein); starvation stools.
• Surgical conditions: appendicitis; intussusception; partial bowel obstruction, e.g. volvulus, Hirschsprung's disease; Meckel's diverticulum; short bowel syndrome.
• Malabsorption: cystic fibrosis, coeliac disease.
• Inflammation: ulcerative colitis, Crohn's disease.
• Miscellaneous: constipation with overflow, haemolytic-uraemic syndrome, toddler diarrhoea.

Presentation

• May or may not be otherwise unwell with systemic symptoms.
• Food history can be helpful. Anyone else in family affected.
• Non-specific non-focal abdominal pain and cramping are common.
• Water exposure: swimming pools have been associated with outbreaks of Shigella, Giardia, Cryptosporidium and Entamoeba. These organisms are resistant to water chlorination.
• Travel history may indicate a cause for diarrhoea. Enterotoxigenic E.coli is the leading cause of traveller's diarrhoea.
• Animal exposure: e.g. exposure to young dogs or cats is associated with Campylobacter.
• Signs:
  • Dehydration is the principal cause of morbidity and mortality. Loss of more than 10% body weight will lead to shock with falling blood pressure and tachycardia, coma and anuria.¹
  • 5% dehydration: loss of skin turgor, fontanelle may be slightly depressed, eyes are slightly sunken, peripheral pulses are normal, mental state may be normal or may be lethargic.
  • 10% dehydration: skin is mottled with poor capillary return, fontanelle is deeply depressed, eyes are deeply sunken, tachycardic with poor volume pulse, severe lethargy, prostration, coma.
  • May be evidence of failure to thrive and malnutrition.
  • Abdominal pain: pain does not increase with palpation. Focal abdominal pain worse on palpation, rebound tenderness, or guarding need further assessment (usually urgent hospital admission for possible appendicitis).

Investigations

• Stool culture: including examination for ova, cysts and parasites.
• Rotavirus antigen tests: false-negative rate is approximately 50%, and false-positive results occur, particularly in the presence of blood in the stools. Adenovirus (serotype 40 and 41) antigen can be detected by enzyme immunoassay.
• White cell count is usually normal but may be raised in some bacterial infections.
• Renal function and electrolytes. Occasionally a protein-losing enteropathy may lead to a low serum albumin.
• Other investigations will depend on individual situation. Further investigations may include endomysial antibodies, intestinal biopsy (coeliac disease), sweat test (cystic fibrosis) if indicated, especially if diarrhoea persists.

Management²

• Most infectious diarrhoea is self-limiting and medical care is mainly supportive. The important aspects of management are recognition of more serious causes of diarrhoea, and adequate oral rehydration at an early stage. Infants under six months of age are at greatest risk of dehydration.
• The majority of children can be managed safely in the community, but there should be a lower threshold for admission to hospital for infants under six months. Small amounts of fluid given frequently are often tolerated even when vomiting has been a prominent symptom.
• Breast feeding: continued use of breast milk has been shown to be beneficial in children with acute diarrhoea.
• In treatment of diarrhoea, the most important factor is to maintain hydration. Studies have found no significant difference between oral rehydration solutions and intravenous fluids in duration of diarrhoea, time spent in hospital, or weight gain at discharge. Nasogastric rehydration in hospital has been found to be as effective as intravenous fluids.³
• Continuing or early resumption of normal feeding hastens recovery and should be strongly encouraged.³
• Lactose-free feeds may reduce the duration of diarrhoea but the evidence is unclear.⁴
• Antibiotic therapy is nearly always inappropriate in view of the usual viral aetiology, usually self-limiting and the possibility of causing pseudomembranous colitis. When required, antibiotic regimes will be determined by the results of stool culture and sensitivities and local guidelines.
• Loperamide has been shown to reduce the duration of diarrhoea, but adverse effects are unclear and it should not be prescribed.
• Consider hospital admission if:
  • Any concern regarding the underlying diagnosis.
  • Signs of dehydration especially if under six months.
  • Inability to comply with oral rehydration, e.g. vomiting, poor social circumstances.
  • Pre-existing medical condition which may worsen with diarrhoea (e.g. diabetes).

Complications

• Rotavirus infection may lead to dehydration and also lactose intolerance.
• Bacterial bowel infection may rarely lead to infection at other sites, including septicaemia, meningitis and osteomyelitis. Infection may also lead to bowel perforation, intussusception, appendicitis or liver abscess. These complications are very uncommon but need to be considered if the child is particularly unwell or not making the expected recovery.
• Other rare complications include haemolytic uraemic syndrome and Reiter's syndrome.
• Giardia infection may lead to chronic fat malabsorption.
• Carrier states are observed after some infections, e.g. rotavirus and Salmonella infections.
• E.coli O157:H7 is the most common, but not only, cause of haemolytic uraemic syndrome. It may also cause haemorrhagic colitis.

Prognosis

• With proper management, prognosis is very good in developed countries.
• Mortality is caused predominantly by dehydration and secondary malnutrition.
• Neonates and young infants are at particular risk of dehydration and malnutrition.

Prevention

• Food hygiene (storage, handling, cooking).
• Hand washing.
• Appropriate exclusion of children with diarrhoea, e.g. from nurseries.
• Vaccination: rotavirus vaccine has been associated with an increased incidence of intussusception and is currently not available. Salmonella typhi vaccine is recommended for travellers to countries with a high incidence. Vibrio species vaccine is available but only protects 50% of immunised persons for 3-6 months and is not indicated for use.

Chronic diarrhoea

Diarrhoea lasting more than two weeks, particularly if associated with weight loss, needs further investigation.

Differential diagnosis

• Well child with no weight loss:
  • Toddler diarrhoea typically occurs in the second year of life and is associated with undigested food such as peas and carrots in the stools. The child is well and growing normally. It is thought to relate to a rapid intestinal transit time. It resolves by the age of 4 years.
  • Breast-fed babies often have liquid and abnormal stools. This is normal and doesn't need any further investigation if the baby is otherwise well and thriving.
• Unwell child with weight loss:
  • Food intolerance e.g. cow's milk protein intolerance.
  • Inability to digest nutrients e.g. pancreatic insufficiency, cystic fibrosis.
  • Small intestinal disease: coeliac disease, food-sensitive enteropathy, inborn error of digestion or absorption, short bowel syndrome.
  • Inflammatory bowel disease: Crohn's, ulcerative colitis.
  • Intestinal parasites: e.g. Giardia lamblia.
  • Chronic enteric infection: stagnant loop syndrome.
  • Iatrogenic: therapeutic diets, drugs (e.g. excessive laxatives).
  • Miscellaneous: e.g. acrodermatitis enteropathica, immunodeficiency, Shwachman-Diamond syndrome, hyperthyroidism.

Investigations

• Stool microscopy, culture and sensitivities; ova, cysts and parasites.
• Endomysial antibodies, jejunal biopsy (coeliac disease).
• Sweat test (cystic fibrosis).
• Blood tests are of limited value although peripheral blood eosinophilia may be present in children with food protein sensitivity. Investigation of immune function may reveal specific abnormalities. Measurement of renal function and electrolytes is particularly important if poor fluid balance.
• Radiological studies are rarely useful but barium meal and follow-through will exclude malrotation and may occasionally demonstrate a blind loop.
• Endoscopy of the upper and lower gastrointestinal tract, with biopsies, may be required.