Diarrhoea Flashcards
What does sudden onset of increased bowel frequency associated with crampy abdominal pains and a fever point to?
Infective cause of diarrhoea
What does increased bowel frequency with loose blood stained stools point to?
IBD
What does the passage of pale, offensive stools that float, often accompanied by loss of appetite and weight loss point to?
Steatorrhoea
What does increased nocturnal bowel frequency and urgency point to?
Organic cause of diarrhoea
What does the passage of frequent, small volume stools (often formed) point to?
Functional cause of diarrhoea
What is osmotic diarrhoea?
Large quantities of non-digestible substances in the bowel cause water to move into the lumen, causing diarrhoea
What is secretory diarrhoea?
The secretion of electrolytes into the lumen in response to a signal, which are followed by water
What is inflammatory diarrhoea?
Where damage to mucosal cells leads to loss of blood and fluid
The decrease in absorptive function causes a build up in malabsorbed substances
What are examples of causes of osmotic diarrhoea?
Certain purgatives
Malabsorptive conditions
What are examples of causes of secretory diarrhoea?
Enterotoxin from e. coli, c. diff and cholera
Hormones
What are examples of causes of inflammatory diarrhoea?
IBD
Coeliac
What are examples of diarrhoea caused by abnormal motility?
Diabetes
Post-vagotomy
Hyperthyroidism
What can acute diarrhoea be accompanied by?
Fever
Abdominal pain
Vomiting
Dehydration
When are investigations necessary for acute diarrhoea?
If it is lasting longer than 5-7 days
What investigations should be done if needed for acute diarrhoea?
Stool culture with c. diff toxin assay
If diagnosis still not made: sigmoidoscopy and rectal biopsy
If diarrhoea lasts longer than 7-10 days, what is then the most likely cause?
IBD because viral and bacterial infective diarrhoea do not last that long
What is the management for acute diarrhoea if needed?
Oral fluid and electrolyte replacement
Rehydration sachets
Anti-diarrhoea drugs may be necessary for short term relief
Antibiotics in gastroenteritis depending on the organism
In chronic diarrhoea with blood what investigation is done?
Colonoscopy with biopsy
Blood tests
In chronic diarrhoea with blood, what will a colonoscopy with biopsy diagnose?
Colonic lesions such as:
UC
CD
Carcinoma
What blood tests are done in chronic diarrhoea as an initial investigation?
FBC
Albumin
Folate B12
Inflammatory markers
What can blood tests diagnose in chronic diarrhoea?
Malabsorption
What further blood tests are done if malabsorption is determined in chronic diarrhoea?
MCV Hb B12 Folate Auto-antibodies
What investigation is done if there is high MCV, low folate and positive auto-antibodies?
Jejunal biopsy
Smear for giardia
What will a jejunal biopsy diagnose in malabsorption with chronic diarrhoea?
Small bowel lesions such as:
Coeliac disease
Tropical sprue
What investigation is done if haemoglobin is low?
MRI or CT
What will an MRI or CT diagnose in malabsorption with chronic diarrhoea?
Small bowel lesions such as:
CD
What investigation is done after further blood tests are normal in malabsorption with diarrhoea?
Pancreatic tests
CT scan/US
Function tests
MRCP/MRI
What can be diagnosed by pancreatic tests in chronic diarrhoea with malabsorption?
Chronic pancreatitis
Carcinoma
What are the initial investigations in chronic diarrhoea without blood?
Flexible sigmoidoscopy
Colonoscopy
Biopsies
What can abnormal colonoscopy and biopsies diagnose in chronic diarrhoea?
Colonic lesions such as:
IBD
Pseudomembranous colitis
What are the next investigations when colonoscopy and biopsies are normal in chronic diarrhoea without blood?
Small bowel imaging Colonoscopy and ileal biopsies Serum VIP Thyroxine SeHCAT
What are the conditions that can be diagnosed by further investigation in chronic diarrhoea without blood when colonoscopy and biopsies are normal?
Bile acid malabsorption Thyrotoxicosis Diabetes VIPoma Parasites Colonic carcinoma
What further investigation is done when melanosis coli is found after colonoscopy and biopsy in chronic diarrhoea without blood?
Look for purgatives
What conditions can be diagnosed after finding melanosis coli and looking for purgatives?
Purgative abuse
Dilutional diarrhoea
What is usually the first investigation if stool cultures are negative and small bowel disease is not suspected?
Colonoscopy with biopsy
What is c. diff associated colitis also known as?
Pseudomembranous colitis
What are the clinical features of c. diff associated colitis?
Diarrhoea ranges from mild to profuse, watery, haemorrhage colitis
Abdominal pain
Colonic mucosa is inflamed and ulcerated
Can cause intractable diarrhoea leading to toxic megacolon and deaths
What are markers of severity of c. diff associated colitis?
High temperature WCC > 15x10^9 Serum creatine 50% above baseline Raised serum lactate Severe abdominal pain
How is diagnosis of c. diff associated colitis made?
The detection of c. diff A or B toxins in the stools using ELISA or PCR
What is the management of mild and severe c. diff associated colitis?
Metronidazole for mild to moderate
Oral vancomycin for severe or relapsing
What is bile acid malabsorption?
The terminal ileum fails to reabsorb bile acids
This leads to diarrhoea, reducing absorption of water and electrolytes
If bile salts are at higher concentrations in the lumen, secretions are also induced and colonic motility is increased, causing more diarrhoea
What are causes of bile acid malabsorption?
Ileal resection Ileal disease (e.g. CD) Primary bile acid diarrhoea Post-infective gastroenteritis Rapid small bowel transit Post-cholecystectomy
How is diagnosis of bile acid malabsorption made?
SeHCAT tests
What is the treatment for bile acid malabsorption?
Bile salt sequestrates (cholecystramine)
What are the features of purgative abuse causing factitious diarrhoea?
High volume diarrhoea
Low serum potassium
Often occurs in association with eating disorders
What can help to diagnose laxative abuse
Biochemical analysis
What is dilutional diarrhoea?
Raised stool weights as a consequence of patients deliberately diluting their stool with urine or tap water
How is diagnosis made for dilutional diarrhoea?
Measurement of stool osmolality and electrolyte concentrations
