Diarrhoea in Children
This is a very common presentation and is usually caused by gastroenteritis or some other acute infection. Less common is the subacute or prolonged case, where the differential is wider and where a referral is required for more detailed analysis.
Differential diagnosis
Common Diagnoses
- Gastroenteritis
- Other Systemic Infection (e.g. UTI, Otitis Media, Pneumonia)
- Toddler’S Diarrhoea
- Medication Side Effects (Usually Antibiotics)
- Cow’s Milk Protein Intolerance (CMPI)
Occasional Diagnoses
- Lactose Intolerance (Typically Following a Bout of Gastroenteritis in Babies)
- Faecal Impaction (Causing Overflow Diarrhoea)
- Irritable Bowel Syndrome
- Coeliac Disease
- Other Gastrointestinal Infections, e.g. Giardia
Rare Diagnoses
- Inflammatory Bowel Disease (IBD)
- Appendicitis (Relatively Common but Rarely Presents with Diarrhoea)
- Intussusception
- Cystic Fibrosis
Ready reckoner
Key distinguishing features of the most common diagnoses
| Gastroenteritis | Other Systemic Infection | Toddler’s Diarrhoea | Medication Side Effects | CMPI | |
|---|---|---|---|---|---|
| Blood in Diarrhoea | Possible | No | No | No | Possible |
| Recent or Current Antibiotics | No | Possible | No | Yes | No |
| Fever | Possible | Possible | No | Possible | No |
| Lasts More than 2 Weeks | Possible | No | Yes | Possible | Yes |
| Other Localising Symptoms (e.g. Respiratory, Urinary or Ear) | No | Yes | No | Possible | No |
Possible investigations
Likely: None.
Possible: Stool culture, urinalysis, MSU, FBC, CRP, ESR, anti-endomysial and anti-gliadin antibodies, faecal calprotectin.
Small Print: Hospital-based tests (e.g. for cystic fibrosis, IBD and to confirm coeliac disease).
- Stool culture: For microbiological examination if the diarrhoea persists more than a week, is bloody or there is relevant recent foreign travel; send three specimens for ova, cysts and parasites if giardia suspected.
- Urinalysis: May help if a UTI is suspected as the underlying cause.
- MSU: For confirmation of a suspected UTI.
- FBC, ESR, CRP: Hb may be reduced, and CRP/ESR raised in IBD.
- Anti-endomysial and anti-gliadin antibodies: If coeliac is a possibility.
- Faecal calprotectin: To help rule out IBD if diarrhoea is prolonged.
- Hospital-based tests: These might include endoscopy and biopsy in suspected IBD or coeliac disease, and tests for possible cystic fibrosis.
Top Tips
- It is not unusual for the diarrhoea in gastroenteritis to take a couple of weeks to settle; consider a stool specimen if it is not starting to improve after a week.
- Don’t overlook faecal impaction as a cause of overflow diarrhoea in children, the clues being soiling and a preceding history of constipation.
- Lactose intolerance tends to be over-diagnosed and often confused with CMPI. The former is less common, typically follows gastroenteritis and is usually short lived.
- Undigested food (‘peas and carrots syndrome’) in the persistent loose stool of an otherwise well and thriving child is virtually pathognomic of the harmless toddler’s diarrhoea.
Red Flags
- In the acute case – particularly in younger children with severe diarrhoea and associated vomiting – assess for dehydration as a priority. If the child is significantly dehydrated, then admission will be needed regardless of cause.
- Bloody diarrhoea raises the stakes somewhat. In the acute situation, this could be one of the more severe forms of gastroenteritis or, especially in those under 1 year of age, intussusception. In more prolonged cases, it might indicate CMPI or IBD.
- Very minor, transient weight loss is common during a bout of gastroenteritis. More prolonged weight loss with persistent diarrhoea should, on the other hand, prompt urgent referral.
- Remember that appendicitis can cause diarrhoea. In such cases, the abdominal pain is usually more marked and constant than in a typical gastroenteritis, where it is typically mild (and therefore not the presenting complaint) and intermittent.