Diarrhoea Flashcards
Two stool tests that may be requested
Stool culture
Faecal calprotectin
Which layer of the bowel wall does uc affect
Mucosa
Infective cause diarrhoea signs
Sudden onset of bowel frequency associated with crampy abdominal pains and a fever
Steatorrhea diarrhoea
Passage of pale, offensive stools that float often accompanied by a loss of appetite and weight loss
What is diarrhoea
The abnormal passage of loose or liquid stool more than 3 times daily
Osmotic water diarrhoea
- Large quantities of non-absorbed hypertonic substances in the bowel draw fluid into the intestine
- Diarrhoea stops when the patient stops eating or the malabsorptive state is discontinued
Causes of osmotic water diarrhoea
- Ingestion of non-absorbable substances e.g. a laxative such as magnesium sulphate
- Generalised malabsorption so that high concentrations of solute e.g. glucose remain in the lumen
- Specific malabsorptive defect e.g. disaccharide deficiency
Secretory - microscopic colitis diarrhoea
- There is active intestinal secretion of fluid and electrolytes as well as decreased absorption
- Continues even when the patient fasts
Causes of secretory microscopic colitis
- Enterotoxins e.g. E.coli and cholera toxin
- Bile salts in colon following ileal disease, resection or idiopathic bile acid malabsorption
- Fatty acids in colon following ileal resection
Fat (steatorrhoea):
- Characterised by increase gas, offensive smell and floating hard-to-flush stools
- Giardiasis and coeliac disease can cause steatorrhoea
Inflammatory discharge
- Damage to the intestinal mucosal cell leads to loss of fluid and blood and defective absorption of fluid and electrolytes
- Causes:
- Inflammatory e.g. UC or Crohn’s
- Infective e.g. Shigella or Salmonella
Infective diarrhoea epidemiology
- 2nd leading cause of death in children under 5 globally - after Pneumonia
- Highest prevalence in South Asia and Africa
Viral causes of infective diarrhoea
- Rotavirus - leading cause of diarrhoea illness in young children, affects nearly all children by the age of 4
- Norovirus - most common among adults. Associated with; cruise ships, hospitals, restaurants - close proximity of people
- ## Adenovirus: a less common cause and presents with a more subacute diarrhoea
C. difficile diarrhoea
In general, antibiotics beginning with C can give rise to antibiotic
induced Clostridium difficile diarrhoea
Clostridium difficile replaces normal gut flora (e.g. when normal gut flora die due to antibiotic use) and causes necrosis giving rise to pseudomembranous colitis. This results in diarrhoea
E.Coli diarrhoea
more common in children
Infected faces, unwashed salads and water
Travellers diarrhoea
Produces shiga toxin - abdominal cramps, bloody diarrhoea and vomiting - destroys blood cells > heamolytic uraemic syndrome
Salmonella Diarrhoea
- more common in children
- Spread by eating raw eggs or poultry and food contaminated with infected faeces of small animals
Shigella diarrhoea
- more common in children
- Spread by faeces contaminating drinking water, swimming pools and food.
- Shigella can produce the Shiga toxin and cause haemolytic uraemic syndrome.
Campylobacter jejuni (most common, associated with poultry)
- Most common bacterial cause of gastroenteritis worldwide.
- Common cause of travellers diarrhoea.
- Spread by raw or improperly cooked poultry, untreated water, unpasteurised milk
RFs for diarrhoea
Foreign travel
Poor hygiene
Elderly
Antibiotics
Immunocomprimised
S + S
- Bloody diarrhoea - associated with bacterial infection (salmonella, shigella, e.coli)
- Vomiting
- Abdominal cramping
- Fever fatigue headache
Investigations for diarrhoea
-
Bloods -
- Low MCV and/or Fe deficiency e.g. in coeliac disease or colon cancer
- High MCV if alcohol abuse or decreased B12 absorption e.g. coeliac disease or Crohn’s
- Raised white cell count if parasites
- Stool MCS - establish the causative organism and antibiotic sensitivities
- Abdominal xray - for toxic megacolon in case of C.diff
- Sigmoidoscopy with biopsy
DDs
- Appendicitis
- Volvulus
- IBD
- UTI
C. difficile management
- Metronidazole
- Oral vancomycin
- Rifampicin/Rifaximin
- Stop C antibiotic
In general management
- Isolate patient
- Good hygiene
- Treat causes
- IV fluids if severely dehydrated
- Oral rehydration and avoid high-sugar drinks in children (increases diarrhoea)
- Antibiotics, where appropriate
List 4 important features in the history the GP should enquire about to establish the cause of the diarrhoea?
Contact with anyone else with diarrhoea,
presence of blood or mucus in the stool,
presence of abdominal pain, history of recent foreign travel,
family history of bowel problems,
presence of bloating, weight loss, clarify what patient means by diarrhoea – consistency etc
Two blood tests to differentiate between the different causes of diarrhoea
Fbc
Esr
Crp
