29 -. Diarrhoeal Disease Flashcards
Why does the definition of diarrhoea have little clinical value?
People don’t measure their stool and there is no normal bowel habit (greater than 200g and 3 times a day)
What is important in diarrhoea
Knowing what is normal for the individual patient and so when a change in bowel habit is occurring
What 2 things do you need to diagnose diarrhoea
loose consistency and increased frequency
Boundary between acute and chronic diarrhoea
14 days
What is most acute diarrhoea caused by
bacterial infection (99%)
Causes of acute diarrhoea
- viral, parasitic, bacterial infection
- salmonella
- E Coli
- campylobacter
- cholera
- staph
- norovirus
- CMV
- rotavirus
Chronic diarrhoea causes
Many causes so grouped according mechanism but several mechanisms can contribute at once
- Inflammatory
- Secretory
- Osmotic
- FATTY
Inflammatory
Damaged epithelium leads to exudate/excessive secretion. May be BLOOD (only kind of diarrhoea where there is blood)
Secretory
Is an active process where there is stimulation causing excessive fluid secretion (similar to inflam but no inflam)
Osmotic
Increase in osmotic load in colon drags in water
Fatty
(also see steatorrhoea)
due to fat malabsortion
bulky, pale, oily and hard to flush
If there is blood in the diarrhoea what must the mechanism be?
Inflammatory chronic diarrhoea
Are all mechanisms of acute diarrhoea the same
no even though they are all grouped under infective different bacteria use different mechanisms i.e.
- Campylobacter causes mucosal inflammation
- Giardia causes villous atrophy > malabs > osmotic
- E coli causes secretory
What can cause inflammatory diarrhoea
- IBD
- Diverticulitis
- SI Bacterial Overgrowth (SIBO)
- radiation and ischaemic colitis
- colon cancer
Diverticulitis
Inflammation of diverticula that usually occur due to constipation due to it being blocked with stool
SIBO and inflam diarrhoea
- the bacteria cause direct damage and inflammation of enterocytes
- often occurs in people who have had surgery or motility problems that allow the bacteria to proliferate
What can cause osmotic diarrhoea
> usually due to malabsorption
- carbohydrate malabsorption; lactose intolerance and celiac
- IBS
- SIBO
- laxative abuse
SIBO and osmotic diarrhoea
By products of bacteria are osmotically active
What can cause secretory diarrhoea
> when colon is irritated so secretes to flush
- terminal ileum resection
- causes bile acid malabs > irritates bowel
- cholecystectomy; GB removal so bile straight into SI
- microscopic colitis
- inflammatory and collagenous
- IBD
- Diverticulitis
- Neuroendocrine tumours
- SIBO
- Disordered motility such as IBS
- Colon Cancer
- Laxative abuse
- Addison’s disease