Diarrhoea

Question 1

Why is there little clinical value in ‘standard measures’ of normal and abnormal stools?

Answer 1

It is hard to determine what is normal, many people are different, so instead look at what is normal for the PATIENT.

Question 2

medical aid designed to classify poop consistency?

Answer 2

Bristol Stool Chart.

This is helpful for the patient.

Question 3

How can you determine acute vs chronic diarrhoea? How do their causes differ?

Answer 3

Acute= upto 14 days
95% infectious cause
Chronic = over 14 days
many different causes

Therefore it’s important to ask patient for TIME FRAME

Question 4

Causes of Acute Diarrhoea?

Answer 4

INFECTION
1) Bacteria- salmonella, E.Coli, campylobacter

2) Viruses- norovirus(rest homes), rotovirus
3) Protozoa

Question 5

Infective causes can have different mechanisms, give examples of this.

Answer 5

Campylobacter > INFLAMMATORY diarrhoea

Glardia > OSMOTIC diarrhoea
mild villous atrophy> carb malabsorption> osmotically active sugars> water drawn in

E.Coli > SECRETORY
toxin stimulates fluid secretion

Question 6

Causes of Chronic diarrhoea

Answer 6

There are many causes that can be grouped into…
Inflammatory: damaged epithelium lead to exudate, eg) IBD

Osmotic: osmtically active compound draws water in

Secretory: stimulation of excessive fluid secretion

Fatty: Fat malabsorption

These are classifications of BOTH acute and chronic, and there is often overlap

Question 7

Inflammatory diarrhoea is often due to

Answer 7

• IBD
• Diverticulitis (diverticula > stool filled > infection > inflamm)
• SIBO (direct inflammation of enterocytes)
• Radiation colitis
• Ischaemic colitis (lack of BF to colon)
• colon cancer

Question 8

Osmotic Diarrhoea is often due to

Answer 8

Carb malabsorption: lactase intolerance, IBS

Coeliac disease

SIBO:: malabsoption of proteins, carbs fats and other osmotically active by-products of bacteria metabolism

Laxative Abuse: (can be OSMOTIC or stimulative)

Question 9

Types of Lactose intolerance

Answer 9

Primary LI: due to lactase deficiency

Secondary LI: due to enterocytes that produce lactase being damaged

Question 10

Secretory Diarrhoea can be caused by

Answer 10

• Terminal Ileal Resection
• Cholecystectomy: GB removed, bile flows straight into SI
• Microscopic Colitis
• IBD
• Diverticulitis
• Neuroendocrine Tumors
• SIBO
• Disordered motility (IBS, post-vagotomy)
• Colon cancer
• Laxative abuse- stimulatory type

Question 11

Neuroendocrine tumors

Answer 11

Rare increase in hormones that can drive water secretion (gastrinoma- excess gastrin, carinoid- excess serotonin)

-secretory diarrhoea

Question 12

How does TI resections cause Secretory diarrhoea

Answer 12

Where BAs are normally absorbed, post-surgery they enter colon (malabsorb), irritate it = fluid response

Question 13

Fatty diarrhoea can be caused by

Answer 13

• Pancreatic Exocrine insufficiency (esp. LIPASE)
• Bile acid malabsorption (not enough bile)
• SIBO
• Coeliacs disease
• Short bowel syndrome (too much SI removed, not enough surface)

Question 14

What is SIBO? Symptoms?

Answer 14

Small Intestine Bacterial Overgrowth
-Excessive amounts of LI bacteria in the SI

Symptoms (siimilar to IBS): bloating/abdo discomfort, diarrhoea, flatulence, steatorrhea, malabsorption

Question 15

Predisposers of SIBO

Answer 15

Impaired motility- usually a motor complex prevents SIBO by clearing debris eg) scleroderma, diabetes

Anatomical Disorders- lead to SI stasis. eg) strictures, adhesions, SI diverticula, blind loops

• metabolic/systemic diseases
• immune deficiency

Question 16

How does SIBO affect MALDIGESTION

Answer 16

• bacteria deconjugate BAs leading to impaired micellar formation and fat digestion (FATTY DIR.)
• Bacterial degradation of carbs in the intestinal lumen > osmo active byproducts (OSOTIC DIR.)
• bacterial degradation of protein precursors

Question 17

How does SIBO affect MALABSORPTION

Answer 17

bacteria can directly damage enterocytes by direct adherence > enterotoxins (INFLAMMATORY DIR)
leads to malabsorption of
-BAs
-fats
-carbs
-proteins
-B12 (bacteria competes with B12 for nutrition)
(SECRETORY DIR)

Question 18

what type of diarrhoea can SIBO cause

Answer 18

all four types

Question 19

Maelena

Answer 19

Black stools. indicates bleeding from upper GI track (SI). Digested blood is altered by acid

Question 20

Delayed vomiting after meals suggests?

Answer 20

Pyloric obstruction

Question 21

Ulcers around the pylorus

Answer 21

eg) pre-pyloric or duodenal
cause a distrotion of the normal pylorus, this can lead to a change in gastric emptying, pain and eventually fibrosis.

Over months a pyloric stenosis can formed, blocking food.

if an ulcer gets deep enough, active bleeding > maelena

Question 22

Pyloric Stenosis (obstruction) is treated with?

Answer 22

1) Endoscopic balloon dilation (temp fix)
2) gastro-jejunostomy and truncal vagotomy (cut bits out)
eg) billroth 1 & 2 -distal stomach and prox duodenum removed

3) now lots of successful drugs (surgery uncommon)

Question 23

What can happen post gastro-jejunostomy and truncal vagotomy?

Answer 23

Upper Abdo discomfort after eating.

• rapid gastric emptying as no pylorus
• High osmotic load pulls fluid into jejunum

Diarrhoea

• Osmotic diarrhoea
• vagotomy leads to increased SI motility

Question 24

Why is the symptoms bleeding with diarrhoea helpful?

Answer 24

Because it only occurs with inflammatory diarrhoea.

Therefore excludes many other potential causes

Question 25

Colectomy

Answer 25

Surgical procedure to remove all or part of the colon. Can sometimes be avoided with instead using some drugs. However, if people fail to respond to medication, a colectomy and/or ileostomy may be done

Question 26

Ileostomy is?

Answer 26

Usually done in parr with a colonoscopy, where all or part of the LI is removed. SI taken to the skin at the mid-portion of the abdomen, usually on the right, contents emptied into a bag. Patients empty this bag several times a day. When your ileostomy is temporary it most often means all of your large intestine was removed but you still have at least part of your rectum. Some are permanent

Question 27

Usual Ileostomy output

Answer 27

0.6-1L/day thick fluid dark green/brown -no odour (no bacteria) Contains electrolyes, increased sodium loss. Kidneys usually adapt to this and increase sodium reabsorption. Increase sodium intake

Question 28

How can you decrease small bowel motility?

Answer 28

With medication loperamide (anti-diarrhoea agent) so absorption is increased

Question 29

Crohns Disease

Answer 29

Chronic inflammatory condition that can occur at any part of the GI tract (usually colon or TI). Over time fibrous/scarring occurs, and this can lead to strictures. The narrowing of the SI is a common complication, there are drugs to fix BUT once it becomes a fibrotic stricture the meds wont work (they only target inflamm). Then an operation would be needed

Question 30

Two common consequences of Crohns disease.

Answer 30

1) B12 malabsorbtion- loss of TI's specialised receptors for B12/IF 2) Bile salt malabsorption- reduced reuptake of bile salts via enterohepatic circ, instead lost thrugh colon/faeces, where they irritate the colon > water and electrolyte sectretion (secretory dir.) Also the lack of BAs leads to fat malabsorbtion (Fatty dir.) Usually one of the two dirrhoeas will predominate/drive

Question 31

A drug that binds BAs (used for Crohns)

Answer 31

Cholestryamine

Question 32

Short Bowel Syndrome

Answer 32

Too much SI removed, complication of SI surgery, leads to malsborption of everything. - vitamins, minerals - water, electrolytes - proteins, fats, carbs - bile acids People with colon and illeocaecal valve do better. colon reabsorbs water valve acts as brake

Question 33

Adaption to Short bowel syndrome. If this doesn't work, how is it managed?

Answer 33

Ileal adaption: villi hypertrophy Colon increases water absorption ``` Dietary (iso-osmotic) Anti-motility drugs (slow down) Acid suppressant meds Cholestyramine TPN (IVF) ```