IBS and Diverticulous Disease

Question 0

Is there a predominant patter of motility changes in IBS?

Answer 0

No, but 25% of people have IBS-C (constipation-type).

Question 1

Criteria for Irritable Bowel Syndrome (IBS) diagnosis? Duration?

Answer 1

Recurrent abdominal pain or discomfort with at least 2 of:
- Improved with defecation.
- Associated with change in frequency of stool.
- Associated with change in form of stool (watery or hard).
Happens at least 3x / mo for at least 3 months.
(with exclusion of an “organic” disorder)

Question 2

What might be responsible for the increased motility observed in IBS-D (diarrhea-type)?

Answer 2

Exaggerated motor response to CCK and feeding.

Question 3

How are gut afferents different in IBS?

Answer 3

They seem to be more sensitive to normal stimulus.

or they were sensitized by some abnormal stimulus

Question 4

3 ways visceral hypersensitivity could happen?

Answer 4

Overreaction to normal.
Sensitization by abnormal stimulus (eg. excess gas).
Abnormal central pain processing?

Question 5

What does bloating have to do with IBS?

Answer 5

People with IBS seem to have more gas in their bowels, and their more sensitive to distension.

Question 6

Are there CNS differences in IBS patients vs. controls?

Answer 6

Yes. They seem to have more activity in emotional arousal and pain regions in response to rectal distension.
(where this disease has overlap with psych stuff?)

Question 8

Is the microbiome different in patients with IBS?

Answer 8

Yes, they tend to have less “good” bacteria, such as bifidobacterium.
(and ABx can help sometimes…)

Question 9

Can IBS be precipitated by infection?

Answer 9

Seems to be.

or maybe people likely to develop IBS are more susceptible to GI infection…

Question 10

What’s SIBO? What does that have to do with IBS?

Answer 10

Small intestine bacterial overgrowth.

Increased number and/or type of bacteria in upper GI tract -> more gas, etc.

Question 11

What are some molecules that may be particularly bad for IBS?

Answer 11

FODMAPs -(oligosacchardies, disaccharides, monosaccharides, polyols) - don’t get broken down by us, rather fermented by gut flora.

Question 12

When is fiber bad for IBS?

Answer 12

When it’s fermented by bacteria.

Question 13

What effect can lipids have on patients with IBS?

Answer 13

Lipids in the small bowel seem to slow motility and make it think it’s distended… in IBS this can be perceived as pain and urgency.

Question 14

Can gluten cause symptoms in IBS patients without celiac disease?

Answer 14

Seems to..

Question 15

Some immune changes in IBS?

Answer 15

More inflammation - Mast cells, 5-HT release, lymphocytes, permeable.

Question 16

4 categories of genetic alteration associated with IBS?

Answer 16

Susceptibility to inflammation.
More bile acid synth (less neg feedback).
Altered neurotransmitter / cytokine activity.
Alteration the the guanylate cyclase C secretory pathway (???).

Question 17

Psych things that lots of IBS patients have?

Answer 17

Early Adverse Life events
More anxiety, depression, phobias, and somatization.
Hyperactive HPA axis…

Question 18

What is diverticulosis?

Answer 18

The presence of diverticula - sac-like projections.

Question 19

What’s the difference between a false and true diverticulum?

Answer 19

False - just composed of mucosa and serosa.

True - composed of all layers.

Question 20

Possible historic dietary shift responsible for more diverticulosis?

Answer 20

Disappearance of fiber from diet with new milling techniques.
(correlation)

Question 21

Pattern of who gets diverticula?

Answer 21

More as people age. Up yo 65% of people have them at age 80.

Question 22

Most common part colon for diverticulosis?

Answer 22

The sigmoid colon.

Question 23

5 factors contributing to diverticulosis?

Answer 23

Diet
Anatomic weakness
Increased intraluminal pressure
Disordered motility
Neurotransmitters

Question 24

Review: On what side of the colon do diverticula develop?

Answer 24

Where the vasa recta penetrate the circular muscle layer.

Question 25

Why might diverticula be more likely to develop in the sigmoid colon?

Answer 25

Smaller radius -> higher pressure.

Question 26

How does diverticulosis start?

Answer 26

Elastin deposition -> thickened taenia coli.

Question 27

What kind of collagen gets deposited in diverticulosis? What effect does this have?

Answer 27

Type III Collagen.

This causes increased rigidity and inability to accomodate pressure.

Question 28

What role does segmentation play in forming diverticula?

Answer 28

Causes focal areas of high pressure -> outpouching.

Question 29

What might be wrong with motility in diverticulosis?

Answer 29

Increased segmental contractile activity; i.e. higher spikes of pressure.

Question 30

4 neurotransmitter changes in diverticulosis? Net effect?

Answer 30

Increased 5-HT.
Increased ACh.
Decreased NO.
Decreased vasoactive intestinal peptide.
Net effect: increased motility and increased colonic pressure.

Question 31

3 factors that contribute to developing symptoms from diverticula?

Answer 31

Diet (low fiber, high fat).
Lack of physical activty.
Obesity.

Question 32

3 types of diverticular disease?

Answer 32

Diverticulitis (acute or chronic).
SCAD
SUDD

Question 33

What is SCAD?

Answer 33

Segmental colitis associated with diverticulosis.

Question 34

What is SUDD?

Answer 34

Symptomatic uncomplicated diverticular disease.

-persistant GI symptoms from the diverticulosis without macroscopic colitis or diverticulitis.

Question 35

What are 3 bad outcomes of diverticulitis?

Answer 35

Perforation leading to..
Obstruction
Fistula
Peritonitis

Question 36

4 areas of overlap between IBS and diverticular disease?

Answer 36

Low grade inflammation.
Alterations in gut microbiome (fecal stasis -> alterations?).
Abnormal colon motility.
Visceral hypersensitivity.

Question 37

What’s the deal with diverticular bleeding?

Answer 37

These things tend to form where blood vessels penetrate the colon… leaving a vulnerable blood vessel hanging out on the surface of the diverticulum.