Gastroenterology: Diarrhoea

Question 1

How many stool per day is classified as diarrhoea? [1]
What is acute diarrhoea? [1]
What is chronic diarrhoea? [1]

Answer 1

Diarrhoea: > 3 loose or watery stool per day

Acute diarrhoea < 14 days

Chronic diarrhoea > 14 days

Question 2

What does FIT test screen for? [1]

Answer 2

Positive result: 1/4 chance of colorectal cancer

Question 3

State 7 red flags for cancer w/ diarrhoea [7]

Answer 3

1. Change in bowel habit
2. Bleeding
3. Weight loss, unintentional
4. FH bowel or ovarian cancer
5. > 50 and for >6 weeks
6. Anaemia (anyone who doesnt have periods and has IDA has colorectal cancer until proven otherwise)
7. Abdominal or rectal mass}

Question 4

What are normal bowel movements? [1]

Answer 4

3x a day to 3x a week

Question 5

What is osmotic diarrhoea caused by? [3]

Answer 5

• presence of osmotically active, poorly absorbed solutes in the bowel lumen that inhibit normal water and electrolyte absorption
• high concentration of solute in malabsorption
• disaccharide deficiency

Question 6

What causes secretory diarrhoea? [5]

Answer 6

Excess secretion of water:
- IBD
- Salmonella infection
- Enterotoxins: E. coli, V. cholera
- Bile salts
- Hormones

Question 7

Give three examples of motility related diarrhoea [3]

Answer 7

• Thyrotoxicosis
• IBS
• DM autonomic neuropathy

Question 8

How do you differentiate between secretory or osmotic diarrhoea? [1]

Answer 8

Osmotic: stops when fasting
Secretory: does not stop when fasting}

Question 9

Describe 4 causes of acute diarrhoea? [4]

Answer 9

· Dietary indiscretion: may cause diarrhoea that lasts for a few hours

· Viral infections: are common and often associated with vomiting (I.e. norovirus), often lasts 1-2 days

· Food poisoning: usually due to bacterial infection, is usually a few days longer

· Travellers’ diarrhoea can occur when travelling to anywhere in world. It can last 2-5 days or longer

Question 10

How do you treat acute diarrhoea? [2]

Answer 10

ORS if severe
Culture stool if persistent & severe

Question 11

Acute traveller’s diarrhoea is most commonly caused by which bacteria? [1]

Answer 11

enterotoxigenic E. coli

Question 12

Name two causes of steatorrhoea [2]

Answer 12

• Pancreatic insufficiency
• Small intestine disease

Question 13

How do you distinguish between steatorrhoea from pancreatic insufficiency and small intestine disease? [4]

Answer 13

Pancreatic insufficiency:
- High faecal fat (rare to test now)
- High faecal elastase (more common to test)
- Normal red cell folate
- Pancreatic calcification on US

Small intestinal disease:
- low red cell folate (folate is absorbed higher up GI)
- anti-TTG: CD
- CT
- XR}

Question 14

What does stool in the night indicate? [1]

Answer 14

Organic cause of disease (e.g. rare for it to be IBS)

Question 15

What would the following symptoms indicate about the infective cause of diarrhoea?

· Rapid onset of symptoms (within a few hours after eating) [1]

· Fever [1]

· Bloody diarrhoea [1]

· Abx [1]

Answer 15

Rapid onset of symptoms: (within a few hours after eating)
- this may be from a toxin-producing organism (i.e. reheated takeaways/rice from B.cereus, S.aureus from creamy products)

Fever
- is associated with invasive bacteria: such as campylobacter, salmonella, shigella), enteric viruses, and cytotoxic organisms such as C.dificile, E.histolytica.

Bloody diarrhoea
- is caused by invasive bacteria (is termed dysentery, bacillary dysentery).

Abx
- is associated with C.dificile

Question 16

Which therapeutic drugs are associated with chronic diarrhoea? [8]

Answer 16

1. Alcohol
2. Antibiotics
3. Anti-depressants (lithium, SSRIs)
4. Anti-hypertensives
5. Statins / Cholesterol-lowering agents
6. GI drugs (Mg++, H2RA, PG analogs, 5-ASA)
7. NSAIDs
8. Oral hypoglycaemics like biguanides

Question 17

What is the second most common cause of traveller’s diarrhoea? [1]

Answer 17

Camopylobacter jejuni

Question 18

What is the treatment for C.difficile? [3]

Answer 18

• oral metronidazole
• vancomycin
• faecal microbiota transplant

Question 19

Describe the blood tests for diarrhoea [7]

Answer 19

• FBC: check for anaemia
• WCC platelets, CRP: for signs of infection / inflammation
• U&E: signs of AKI / dehydration
• Albumin, Ca, P – give info on nutritional status
• Haematinics: folate absorbed in proximal small bowel, B12 absorbed in stomach and distal small bowel
• IgA TTG antibodies for coeliac disease
• TFTs: undiagnosed thyrotoxicosis can cause chronic diarrhoea

Question 20

Describe stool test for diarrhoea investigations [5]

Answer 20

• Stool weight: useful but difficult to do in practice
• Culture stool for infection: MC&S, cysts, ova, parasites, CDT
• Faecal calprotectin: (protein produced by neutrophils so inflammation in bowel increases the amount of calprotectin shed so will show up in a stool specimen): easy test for infection and IBD, commonly used in follow-ups for IBD patients
• Faecal immunochemical test for Hb: highly specific test for blood in the stool - colorectal cancer
• Faecal elastase looks for pancreatic disease
• Stool pH / electrolyte balance / reducing substances (see if patients are taking laxatives)

Question 21

What is the gold standard for investigating diarrhoea? [1]

Answer 21

Colonoscopy & biopsy
(Also:
- Duodendal biopsy
- Small bowel MRI
- Video capsule endoscopy
- Cross sectional imaging)
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Question 22

Which viruses commonly cause viral gastroenteritis? [3]

Answer 22

Rotavirus
Norovirus
Adenovirus (tends to cause respiratory symptoms)

Question 23

E. coli produces which toxin? [1]
Which syndrome can it lead to and why? [2]

Answer 23

Produces Shiga toxin
Leads to haemolytic uraemic syndrome due to destruction of rbc

Question 24

How do you treat Campylobacter jejuni infection? [3]

Answer 24

• Clathromycin (1st line)
• Azithromycin
• Ciprofloxacin

Question 25

A patient has recently eaten fried rice left at room temperature. They are reported vomitting and then diarrhoea.

What is the most likely pathogen causing these symptoms? [1]

Answer 25

Bacillus cereus

Question 26

How can you differentiate between Bacillus cereus causing diarrhoea compared to other infective agents? [1]

Answer 26

Bacillus cereus causes vomiting for 5hrs; then diarrhoea for 8hrs}

Question 27

What syndrome can Shigella cause? [1]
Name two treatments [2]

Answer 27

haemolytic uraemic syndrome:

Treatment of severe cases is with azithromycin or ciprofloxacin.

Question 28

A patient presents with diarrhoea, right sided abdominal pain and fever.
What is the most likely cause of infection? [1]
What is a differential diagnosis? [1]

Answer 28

Yersinia enterocolitica: diarrhoea, right sided abdominal pain and fever.

Right sided abdominal pain is caused by mesenteric lymphadenitis (inflammation in the intestinal lymph nodes): appears like appendicitis}

Question 29

Which parasite is found in the small intestines of mammals and causes diarrhoea via a faecal-oral transmission? [1]

Answer 29

Giardia lamblia

Question 30

How do you treat Giardia lamblia? [2]

Answer 30

tinidazole or metronidazole

Question 31

A faecal stool sample was sent, and the results this morning are as follows:

C. difficile toxin -ve
C. difficile antigen +ve

What is the next step in the management of this patient? [1]

Explain your answer [1]

Answer 31

C. difficile antigen positivity only shows exposure to the bacteria, rather than current infection

If the toxin is positive, it means the bacteria is actively replicating and is likely the cause of the diarrhoea.

If the antigen is positive in isolation, it merely means the bowel is colonised with C. difficile, and not necessarily causing diarrhoea.

Reassure and continue monitoring symptoms

Question 32

Which drug classes are risk factors for C. diff infection? [2]

Answer 32

Antibiotics
PPIs

Question 33

[] is a severe inflammation of the inner lining of the large intestine, manifests as an antibiotic-associated colonic inflammatory complication.

What is the most common cause of this? [1]

How does this present? [1]

Answer 33

Pseudomembranous colitis, a severe inflammation of the inner lining of the large intestine, manifests as an antibiotic-associated colonic inflammatory complication.

The most common cause of this is clostridium difficile infection, which can present on sigmoidoscopy with yellow plaques on the intraluminal wall of the colon.

Question 34

The [] is key in determining the severity of C. difficile infection

Answer 34

The white cell count is key in determining the severity of C. difficile infection

Question 35

Which antibiotics are most likely to cause C. difficile infection? [2]

Answer 35

Second and third-generation cephalosporins are now the leading cause of C. difficile.

Clindamycin is historically associated with causing C. difficile but the aetiology has evolved significantly over the past 10 years.

C. difficile: think C!

Question 36

Describe the proflie of stool from a Gardia lamblia infection [1]
Where is a higher risk of infection? [1]

Answer 36

Giardia causes fat malabsorption, therefore greasy stool can occur.

It is resistant to chlorination, hence risk of transfer in swimming pools.

Question 37

A 45-year-old man returns from a holiday in Thailand suffering from non-bloody diarrhoea. After further questioning he complain of nausea, however, has had no episodes of vomiting. His stomach has been painful with stomach cramps for the past 48 hours.

Given this man’s presentation, what is the most likely cause of his symptoms?

Crohn’s disease
Irritable bowel syndrome
Infection by enterotoxigenic E.coli
Infection by C. jejuni
Infection by C. difficile

Answer 37

A 45-year-old man returns from a holiday in Thailand suffering from non-bloody diarrhoea. After further questioning he complain of nausea, however, has had no episodes of vomiting. His stomach has been painful with stomach cramps for the past 48 hours.

Given this man’s presentation, what is the most likely cause of his symptoms?

Infection by enterotoxigenic E.coli
Watery travellers diarrhoea with stomach cramps and nausea, think Enterotoxigenic E. coli