Diarrhoea
A change in stool consistency to watery or loose, with >3 episodes or >200g stool in 24/24.
- Acute: <14 days
- Persistent: 14-30 days
- Chronic: >30 days
Differential Diagnosis for diarrhoeal illness is broad. Consider:
- mesenteric ischemia
- appendicitis, bowel obstruction, volvulus, diverticular disease,
- fecal impaction/incontinence
- GI cancers, GI bleed
- IBD, toxic megacolon
- hyperthyroidism, pancreatic insufficiency
- lactose intolerance, etc.
| Infectious: 80-85% | Non-infectious: 10-15% | ||
|---|---|---|---|
| Viral 60% | Bacterial 20-25% | Parasitic 5% |
|
| • Norovirus • Rotavirus (kids) | • E Coli, Campylobacter • Salmonella, Shigella | • Toxins • medication side effects • osmotic food and drink • underlying GI pathology (IBD, malignancy, etc) |
|
| Small bowel | Large bowel |
|---|---|
| • more likely viral • watery, large volume stools. • Often associated with abdominal cramping, bloating, and gas. • Less commonly febrile. | • more likely bacterial • frequent small volume stools. • may be bloody or mucoid. • Often associated with painful bowel movements. • Fever common |
High risk factors
- Severe abdominal pain
- Bloody or mucoid diarrhoea
- Extremes of age (e.g. >70 years old or <3 months old)
- Known HIV or other immuno-compromise
- Known inflammatory bowel disease
- Co-morbidities exacerbated by hypovolaemia
- Pregnancy
The majority of diarrhoea is non-bloody. The presence of blood suggests:
- shiga-toxin producing E Coli (O157:H7) and Shigella
- occasionally - campylobacter and salmonella
- non-infectious causes - ischaemia, IBD.
Management of bloody diarrhoea
- Antibiotic use is generally not indicated unless a relevant pathogen has been isolated
- Antibiotic use may prolong faecal excretion and usually doesn't affect course of diarrhoea significantly
- Antibiotic use in patients with E Coli O157:H7 is associated with an increased risk of Haemolytic Uraemic Syndrome (HUS)
- anti-motility drugs including narcotics are also generally not indicated, especially in patients with E Coli O157:H7 due to the risk of HUS and the neurological complications associated with HUS
- priority is fluid resuscitation and correction of metabolic abnormalities when relevant
- children with bloody diarrhoea should be admitted
Shiga toxin
- one of the most potent bacterial toxins known.
- found in Shigella dysenteriae type 1 and some serogroups of E coli
- causes bloody diarrhoea and sometimes haemolytic uraemic syndrome (HUS)
- usually from contaminated food or water, though occasionally be passed person-to-person
