IBS and Diverticulosis

Question 1

What is the criteria for IBS?

Answer 1

Recurrent abdominal pain or discomfort at least 3 days/month

Associated with 2 or more of the following:

• improvement with defecation
• change in stool frequency
• change in stool appearance

Question 2

What are the subtypes of IBS?

Answer 2

IBS with constipation
IBS with diarrhea
Mixed IBS

Question 3

Discuss the many factors that contribute to the pathophysiology of IBS

Answer 3

Dysfunction in Brain-Gut Axis
Dysfunction in GI Motility
Visceral Hypersensitivity
Alteration in Fecal Flora
Food
Intestinal Inflammation
Genetic Predisposition
Psychosocial Factors

Question 4

How does GI motility differ between IBS-C and IBS-D

Answer 4

IBS-C: slowed GI motility

IBS-D: increased GI motility and exaggerated motor response to CCK and meal ingestion

Question 5

How does visceral hypersensitivity contribute to/manifest in IBS?

Answer 5

Normally: stimulation of receptors in gut wall –> dorsal horn of spinal cord –> brain

People with IBS have excess and prolonged stimulation of this pathway –> neuronal hypersensitization

Question 6

What are some of the proposed causes of visceral hypersensitivity in IBS?

Answer 6

Increased sensation in response to stimuli (increased awareness at lower distention levels)

Abnormal stimulus (excessive gas, bloating)

Abnormal central pain processing (IBS pts. used pain and emotional arousal modulation centers more than pts. w/o IBS)

Question 7

What is post-infectious IBS? What is the proposed pathophysiology?

Answer 7

Just like it sounds…Increased risk of IBS after infections

GI infection increases intestinal permeability –> inflammation and intestinal microbiota change –> intestinal dysfunction and infection-induced dysbiosis

Question 8

FACT:
Treating SIBO (Small Intestinal Bacterial Overgrowth) reduces IBS symptoms

Answer 8

SIBO = increased number and/or type of bacteria in upper GI tract

Question 9

What kind of carbohydrates cause symptoms in IBS and why?

Answer 9

short chain, poorly absorbed, highly fermentable carbs (FODMAPs)

Since they are fermentable, they produce gas in the intestine

Question 10

Does high fiber diet aggravate IBS?

Answer 10

Yes

Question 11

In IBS, 2hat is the effect of lipids on GI tract in terms of motility and sensitivity

Answer 11

Small intestine - slows motility

Colon - increases motility

Question 12

What is the relationship between gluten and IBS?

Answer 12

Gluten has been shown to cause increased symptoms and increase small bowel permeability in patients with IBS-D (particularly in HLA DQ2/8 positive patients)

*not necessarily people who have Celiac Disease though

Question 13

How is intestinal inflammation related to IBS

Answer 13

changes in mucosal barrier and intestinal permeability- –> intestinal inflammation –> stimulation of enteric nervous system –> abnormal motor and visceral response

Question 14

Is there a genetic predisposition to IBS?

Answer 14

YES

Question 15

Do early adverse life events contribute to IBS?

Answer 15

YESSSS

Question 16

Differentiate between diverticulum and diverticulosis

Answer 16

diverticulum = sac-like protrusion of colonic wall

diverticulosis just means diverticula are present

Question 17

What is the difference between a false diverticulum and a true diverticulum?

Answer 17

False - does not contain all layers of the wall (more common)

True - contains all layers (congenital)

Question 18

Most diverticula are acquired and diverticulosis increases with age

Answer 18

FACT

Question 19

Differentiate between diverticulosis in Westernized nations and in Asia

Answer 19

West = acquired and left sided

Asia = genetic/congenital and right sided

Question 20

Discuss the many factors that contribute to the pathophysiology of diverticulosis

Answer 20

Increased intraluminal pressure

Disordered motility

Neurotransmitters

Anatomic weakness

Dietary factors

Question 21

Where do diverticula usually form?

Answer 21

Develop at points around the colon where vasa recta penetrate the inner circular muscle layer (weak points)

Question 22

What are the muscle layers in the colon? What is their function?

Answer 22

Longitudinal muscle (taeniae coli) pull the colon to shorter functional length

Circular muscle (plicae circulares) control peristalsis

Question 23

How is the muscle altered in diverticulosis because of increased elastin deposition?

Answer 23

Thickened taenia coli –> highly contractile normal muscle –> thickened circular muscle layer –> narrowing of the lumen –> bowel division into segments/compartments

Question 24

How is the muscle altered in diverticulosis because of increased collagen?

Answer 24

Increased rigidity of colon –> decreased compliance –> inability to accommodate pressures

Question 25

How do neurotransmitters play into diverticular disease?

Answer 25

increase in cholinergic activation –> increased motility and colonic pressure

Question 26

Is diverticulosis asymptomatic?

Answer 26

YES it can be

Diverticulosis can be divided into two separate entities

• asymptomatic diverticulosis
• diverticular disease

Diverticular disease can be further divided into diverticulitis and symptomatic uncomplicated diverticular disease (SUDD)

Question 27

What are influential factors in developing symptoms in diverticulosis aka developing to diverticular disease?

Answer 27

Diet
Lack of physical activity
Obesity

Question 28

What are the different types of diverticular disease?

Answer 28

Diverticulitis (acute/chronic)

Segmental colitis associated diverticulosis (SCAD) - form of chronic diverticulitis

Symptomatic uncomplicated diverticular disease (SUDD) - persistent symptoms but no inflammation

Question 29

What is the pathophysiology of diverticulitis?

Answer 29

Erosion of diverticular wall –> inflammation –> focal necrosis –> perforation that can be contained or not contained

Question 30

What is the pathophysiology of diverticular bleeding?

Answer 30

Vasa recta exposed to injury in lumen –> intimal thickening and thinning of the media –> segmental weakness of artery –> rupture into lumen