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GI Week 2 > Lecture 19: Irritable Bowel Syndrome and Diverticulosis > Flashcards

Lecture 19: Irritable Bowel Syndrome and Diverticulosis Flashcards

1
Q

What is gastroenteritis?

A

The stomach flu
Characterized by diarrhea, vomiting and abdominal pain
Caused by rotavirus/noravirus

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2
Q

What is the definition of IBS?

A

Recurrent abdominal pain or discomfort at least 3 days per month for the past 3 months
Associated with two of the following
Pain that leads to
i. improvement with defecation
ii. onset associated with a change in frequency of stool
iii. onset associated with a change in form of stool
A diagnosis of exclusion!!

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3
Q

What are the four categories of IBS?

A
  1. IBS with diarrhea
  2. IBS with constipation
  3. IBS with mixed bowel habits
  4. IBS unclassified type
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4
Q

What are the key characteristics of IBS?

A

Females more at risk than males (the hysterical WOMAN)
No decrease in life expectancy
Enormous host of healthcare utilization and financial loss due to WORK ABSENTEEISM
Avg. 30 sick days per year

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5
Q

What is the most commonly diagnosed GI condition?

A

IBS

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6
Q

What is the etiology of IBS?

A
  1. GI motility
  2. Visceral hypersensitivity
  3. Alteration in Fecal Flora
  4. Food
  5. Intestinal inflammation
  6. Genetic predisposition
  7. Psychosocial Factors
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7
Q

What is the association of motility and IBS?

A

For IBS-C, ~25% of patients have slow colonic transport
For IBS-D, 15-45% of patients have accelerated colonic transit
-increased with meal ingestion and CCK motor response
-increased frequency and irregularity of luminal contractions

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8
Q

What is the association of visceral sensitivity and IBS?

A

Stimulation of receptors of gut wall is very easily stimulated!
Goes to dorsal horn or spinal cord
Brain
Increased sensation in response to stimuli
Possibly an abnormal stimulus (excessive gas)
Possibly abnormal central pain processing
Studies have shown increased levels of awareness and pain in the intestine at lower distension levels

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9
Q

What is the association with bloating and IBS?

A

5-% of patients with IBS (those with constipation) have an increase in abdominal girth with bloating

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10
Q

What is the association of alteration in fecal flora with IBS?

A

Changes in fecal composition have been associated with different disease
Some evidence show microbiota are DIFFERENT in patients with IBS than healthy controls

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11
Q

What drug is used for IBS without constipation?

A

Rifaximin

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12
Q

What does rifaximin do?

A

It is a drug used to improve IBS without constipation

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13
Q

What are the consequences of alteration in GI flora?

A
  1. post-infectious IBS
    • increased risk of IBS after infections
    • associated with bacterial, protozoan, helminth and viral infections
  2. Bacterial overgrowth
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14
Q

What is SIBO? Significance?

A

Small intestinal bacterial overgrowth
-increased number and/or type of bacteria in the upper GI tract
Treating SIBO reduces Symptoms in IBS

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15
Q

What is the association between methane and gut motility?

A

Greater concentration of methane = higher gut motility

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16
Q

What is the association between food sensitivities and IBS?

A
  1. carbs
  2. fibers
  3. lipids
  4. food allergy
  5. gluten sensitivity
    If these guys are poorly absorbed, you get IBS symptoms
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17
Q

What is FODMAPs? Significance?

A

Fermentable by colonic bacteria
Oligosaccharides
Disaccharides
Monosaccharides
And
Polyols
Significance if is that FODMAPs are POORLY ABSORBED
FODMAP + bacteria leads to increase of water absorption in feces
FODMAP + bacteria + water = gas production which leads to DISTENTION

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18
Q

What is the dietary treatment for IBS?

A

FIBER

19
Q

What is the association of lipids effect on the GI tract and what IBS patients feel?

A

When lipids in IBS patients reach small bowel, they reach a small bowle that is more sensitive than usual
This sensitivity causes the following symptoms:
i. IBS-Constipation = patient will feel pain with more motility/sensitivity
ii. IBS-diarrhea = patient will feel urgency to shit with more motility/sensitivity

20
Q

What is the association between food allergy and IBS?

A

When you eliminate allergic foods, patients with elevated IgG titers have reduced IBS symptoms

21
Q

What is the association between intestinal inflammation and IBS?

A

Alterations in particular immune cell markers in some patients with IBS
-mainly with IBS-D and postinfectious IBS
More mast cells = IBS

22
Q

What is the association between mucosal permeability and IBS?

A
  1. Alterations in tight junction
  2. Increased intestinal permeability
  3. Ouflow of antigens
  4. Overstimulation of mucosal immune system
  5. Increased activation of immunocytes (mast cells)
  6. Release of immune factors
23
Q

What is IBS characterized by?

A

-dysmotility
-alteration in sensitivity of GI tract
“irritable” is from the fact that food “irritates” your GI tract, so if you defecate and get rid of the irritant, symptoms go away

24
Q

What are the genetic factors that lead to susceptibility of inflammation of IBS?

A
  1. TNFSF15 mutation = IBS phenotype
  2. TLR9 = postinfectious IBS
  3. KLB (bile acid synthesis) associated with IBS-D and accelerated colonic transit
  4. NpSR1 and FAAH = expression of neurotransmitters and cytokines lead to IBS
  5. Mutations in guanylate cycle C secretory pathway = IBS
25
Q

What are the psychosocial factors that lead to IBS?

A

Neurotic
-prone to negative emotion
Early life events lead to IBS (more lifetime/daily stressful events)

26
Q

How does stress induce alterations in GI function in IBS?

A
  1. GI motility
    • suppressed antral and small bowel motor activity and enhanced colonic motor activity
  2. Visceral perception
    • decreased nonpainful and pain rectal thresholds to distention and stimulation (so it is easier to feel pain)
  3. Emotions
  4. Intestinal permeability and secretion
  5. Autonomic tone
  6. HPA axis
27
Q

What is the association between early adverse life events and IBS?

A

Stress early in life is a risk factor for IBS

Neurotic personality

28
Q

What is diverticulosis?

A

It means that diverticular (sac-like protrusion of colonic wall) are present

29
Q

What is a true diverticulum?

A

Contains all layers of the wall

False diverticulum = does not contain all layers of the wall (e.g. only the mucosa and not the submucosa, etc.)

30
Q

What are the key characteristics of diverticulosis?

A
  1. usually asymptomatic
  2. disease of Western countires and Asians
  3. Most colonic diverticular are acquired
  4. increases with age
    95-99% of people have sigmoid and descending colon diverticulosis
    THICKENING OF COLON and SEGMENTATION
    Forms at points around circumference of colon which vasa recta penetrate the circular muscle layer
31
Q

What is the function of longitudinal muscle?

A

Thickens in thick bands
Pulls the colon to shorter functional length
Taeniae coli

32
Q

What is the function of circular muscle?

A

Thickens regular bands of contraction
Controls peristalsis
Plicae circularis

33
Q

What is a risk factor of diverticulosis?

A

Low fiber diet

34
Q

What is the pathogenesis of diverticulosis?

A
  1. Increased elastin deposition
  2. thickened taenia coli
  3. Highly contractile normal muscle
  4. Thickened circular muscle layer
  5. narrowing of lumen
  6. bowel division into sigements/compartments
  7. decreased compliance (increased rigidity) and inability to accommodate pressures
35
Q

What are risk factors for diverticulosis?

A

a. Dietary factors (less fiber)
b. Anatomic weakness
c. Increased intraluminal pressure (thickening of the muscle layer
d. disordered motility
e. neurotransmitters

36
Q

What are the neurotransmitters that are present in diverticulosis?

A 
Increase in 
	i. serotonin
	ii. acetylcholine
Decrease in
	i. NO
	ii. vasoactive intestinal peptide (VIP)
37
Q

What is diverticulitis?

A

When a diverticulum is inflamed

38
Q

What is SCAD?

A

Segmental Colitis Associated with Diverticulosis
Form of CHRONIC diverticulosis
IBS variant/precursor

39
Q

What is SUDD?

A

Symptomatic uncomplicated diverticular disease

Persistent GI symptoms from diverticulosis without overt macroscopic colitis or diverticulits

40
Q

What is the weakest point in the colon where diverticula develop?

A

Develops at circumference of colon where VASA RECTA penetrate the circular muscle layer
Therefore, if you have higher bowel pressure, you expand basolaterally in diverticulosis

41
Q

Why does rigidity of colon lead to diverticulosis?

A

More rigid you are, the LESS able you are to accommodate pressures by expanding
It’s like catching a football by sticking your chest out

42
Q

What is the pathophysiology of diverticulitis?

A
  1. Erosion of diverticular wall
  2. Inflammation
  3. Focal necrosis
  4. Perforation
    i. contained = obstruction and fistula
    ii. not contained = peritonitis
43
Q

What is the pathophys relationship between Diverticular disease/IBS?

A

Patients with diverticular disease, like IBS had the following
i. visceral hypersensitivity
ii. low-grade inflammation
iii. alterations in gut microbiome
iv. Abnormal colon motility
The point of the bottom chart is to show that pathophys of DD and IBS are VERY SIMILAR

44
Q

What is the pathophysiology of diverticular bleeding?

A
  1. Vasa recta exposed to injury in lumen
  2. Eccentric intimal thickening and thinning of the media
  3. Segmental weakness of artery
  4. Rupture into the lumen

GI Week 2 (15 decks)

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