Diarrhoea

Question 1

What is the name of the poo chart used to describe the nature of poo?

Answer 1

The bristol stool chart

Question 2

How is diarrhoea defined?

Answer 2

Diarrhoea is difficult to define clinically as every individual is different.

It can be defined as:
- greater than 200g/day (although the amount that is considered normal varies for different people so it is best to ask if they think the volume has increased in general)

• loose consistency
• increase in frequency of bowell movements. Once again this should be asked of the patient relative to their normal frequency of bowell movements

Question 3

What is the difference (in terms of duration) or acute and chronic diarrhoea?

Answer 3

Acute = less than/up to 14 days
Chronic = lasts for more than 14 days

Question 4

What are the causes of acute diarrhoea?

Answer 4

Infection infection infection (bacterial, viral, parasitic) (and i guess also laxatives)

Question 5

What are the causes of chronic diarrhoea?

Answer 5

There are a number of causes of chronic diarrhoea and these can be defined by the mechanism through which they arise. The four main mechanisms are:

Inflammatory
Osmotic
Secretory
Fatty

Question 6

Describe inflammatory diarrhoea and some common causes.

Answer 6

Can be caused by a number of different diseases and occurs when the epithelium of the GI tract is damaged which triggers an inflammatory response characterized by exudate (a protein rich fluid that oozes out).

Common causes = inflammatory bowel disease, diverticulitis, small intestinal bacterial overgrowth

Question 7

Describe osmotic diarrhoea and some common causes.

Answer 7

Osmotic diarrhoea is caused due to an accumulation of undigested/unabsorbed nutrients in the intestinal lumen. This results in water flowing out into the lumen to balance the osmolarity.

Common causes = carbohydrate malabsorption (lactose intolerance), coeliac disease (villi are destroyed), small intestine bacterial overgrowth or laxative abuse

Question 8

Describe secretory diarrhoea and some common causes.

Answer 8

Secretory diarrhoea occurs when there is overstimulation of channels in the enterocytes which pump out electrolytes/water.

Common causes =
terminal ileum resection eg due to crohns disease (bile salts can no longer be re-absorbed) or cholecystectomy (gall bladder removed) so there is constant flow of bile acids into the small intestine. In both of these cases, the bile salts/acids are irritants to the small intestine and will result in electrolytes and water being released into the intestines to try and combat the irritation.

Inflammatory bowel disease, diverticulitis, small intestinal bacterial overgrowth.

Question 9

Describe fatty diarrhoea and some common causes.

Answer 9

Fatty diarrhoea occurs when there is fat malabsorption so fat accumulates in the small intestine and passes out in the poo as a thick, fatty stool.

Common causes: Diseases of the pancreas which cause it to not produce enough pancreatic enzymes, bile acid malabsorption, small intestinal bacterial overgrowth, coeliac disease, short bowell syndrome

Question 10

What is small intestinal bacterial overgrowth?

Answer 10

This condition occurs when there is too much bacteria in the small intestine.

Question 11

What are the symptoms of SIBO?

Answer 11

Similar to irritbale bowell syndrome:

Bloating/abdo discomfort, diarrhoea, malabsorption

Question 12

What are some of the causes of SIBO?

Answer 12

problems with motility - the movement of the intestines clears away any debris that might attract bacteria

Immune deficiency disorders

Anatomic disorders that cause stasis in the small intestine eg diverticula, strictures

Question 13

How does SIBO act through the two mechanism of maldigestion and malabsorption?

Answer 13

Maldigestion:

• the bacteria damages/breaksdown bile salts (deconjugates them) which results in impaired fat breakdown and micelle formation
• the bacteria degrades carbohydrates and protein precursors in the intestinal lumen which produces osmostically active by-products

Malabsorption:

• the bacteria adheres to the enterocytes causing damage so they cant absorb the nutrients. They also release enterotoxins and enzymes that prevent absorption.

Question 14

How does SIBO relate to the four main mechanism of chronic diarrhoea?

Answer 14

Fatty/steatorrhea - the the bacteria deconjugates bile acids so they cannot help from micelles and therefore fats cannot be digested and absorbed

Inflammatory - bacteria cause direct inflammation of enterocytes

Osmotic - mal-absorption means that carbohydrate, protein and fat by products create an osmotic imbalance

Secretory - unabsorbed food products and bile salts can have a direct action on stimulating secretory cells of the colon

Question 15

What does melaena indicate about the location of where the bleeding is coming from?

Answer 15

Melaena describes the occurence of black sticky poop. It is black because the haemoglobin from the RBC’s reacts with pancreatic enzymes. Therefore melaena indicates there is bleeding in the upper GI tract. Bleeding in the lower GI tract would appear as brighter red blood as the haemoglobin does not come into contact with any enzymes.

Question 16

Describe the two types of billroth surgeries.

Answer 16

Billroth 1 = antrum/distal portion of stomach is removed along with the pylorus and the remaining stomach is attach to the proximal duodenum.

Billroth 2 = the antrum/distal portion of the stomach is removed and the remainder is attached to the jejunum (gastrojejunostomy)

Question 17

What is an ileostomy?

Answer 17

An ileostomy is an opening in the belly (abdominal wall) that’s made during surgery. The end of the ileum (the lowest part of the small intestine) is brought through this opening to form a stoma (an artificial opening to the gut), usually on the lower right side of the abdomen.

Question 18

Why is an ileostomy performed?

Answer 18

When the bowell has a disease that cant be treated by other methods. The most common reason for having this surgery is inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis.

Question 19

What is a colectomy?

Answer 19

Surgical remove of all or part of the colon.

Question 20

What is a complication of Crohns disease that leads to ileal resection?

Answer 20

Crohns disease (chronic inflammation of the intestines) often leads to damage and fibrosis of the terminal ileum (most commonly) which can cause a stricture (narrowing) of the ileum. When the stricture is fibrotic it often dosent respond well to medication and so it has to resected.

Question 21

What two things are unable to be absorbed when the terminal ileum is resected?

Answer 21

Vitamin B12 and Bile salts

Question 22

What two types of diarrhoea can bile salt malabsorption result in and what determines which diarrhoea type predominates?

Answer 22

Secretory - bile salts are an irritant to the intestines and so electrolytes and water and stimulated to be secreted

Fatty - as most of the bile in our bodies is recycled, there is a shortage of bile in the body when it is excreted in the faeces. A low amount of bile means there is fat malabsorption and so fat appears in the stool.

Whether fatty or secretory diarrhoea occurs depends on the diet of the patient. A fatty diet will mean the person will likely present with fatty diarrhoea and vice versa.

Question 23

What is short bowel syndrome?

Answer 23

Short bowel syndrome occurs as a result of an ileostomy or a small bowel surgery where too much of the bowel is removed.

This results in malabsorption of most micro and macro nutrients as well as water and electrolytes!

Question 24

What is the treatment for small bowel syndrome?

Answer 24

adaptive processes - quite often the bowel can adapt in order to increase absorption in the part of the small intestine that remains eg by enlargement of the villi from hypertrophy or increase in absorptive ability of the colon.

management - low solute/electrolyte diet, anti gastric acid secretion drugs such as omeprazole so that gastric acid dosen’t increase the fluid going into the intestines, cholestyramine (binds to excess bile salts reducing irritation) and in some cases people must be intravenously fed to obtain enough nutrients.