IBS and Diverticulous Disease Flashcards
Is there a predominant patter of motility changes in IBS?
No, but 25% of people have IBS-C (constipation-type).
Criteria for Irritable Bowel Syndrome (IBS) diagnosis? Duration?
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)
What might be responsible for the increased motility observed in IBS-D (diarrhea-type)?
Exaggerated motor response to CCK and feeding.
How are gut afferents different in IBS?
They seem to be more sensitive to normal stimulus.
or they were sensitized by some abnormal stimulus
3 ways visceral hypersensitivity could happen?
Overreaction to normal.
Sensitization by abnormal stimulus (eg. excess gas).
Abnormal central pain processing?
What does bloating have to do with IBS?
People with IBS seem to have more gas in their bowels, and their more sensitive to distension.
Are there CNS differences in IBS patients vs. controls?
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?)
Is the microbiome different in patients with IBS?
Yes, they tend to have less “good” bacteria, such as bifidobacterium.
(and ABx can help sometimes…)
Can IBS be precipitated by infection?
Seems to be.
or maybe people likely to develop IBS are more susceptible to GI infection…
What’s SIBO? What does that have to do with IBS?
Small intestine bacterial overgrowth.
Increased number and/or type of bacteria in upper GI tract -> more gas, etc.
What are some molecules that may be particularly bad for IBS?
FODMAPs -(oligosacchardies, disaccharides, monosaccharides, polyols) - don’t get broken down by us, rather fermented by gut flora.
When is fiber bad for IBS?
When it’s fermented by bacteria.
What effect can lipids have on patients with IBS?
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.
Can gluten cause symptoms in IBS patients without celiac disease?
Seems to..
Some immune changes in IBS?
More inflammation - Mast cells, 5-HT release, lymphocytes, permeable.
4 categories of genetic alteration associated with IBS?
Susceptibility to inflammation.
More bile acid synth (less neg feedback).
Altered neurotransmitter / cytokine activity.
Alteration the the guanylate cyclase C secretory pathway (???).
Psych things that lots of IBS patients have?
Early Adverse Life events
More anxiety, depression, phobias, and somatization.
Hyperactive HPA axis…
What is diverticulosis?
The presence of diverticula - sac-like projections.
What’s the difference between a false and true diverticulum?
False - just composed of mucosa and serosa.
True - composed of all layers.
Possible historic dietary shift responsible for more diverticulosis?
Disappearance of fiber from diet with new milling techniques.
(correlation)
Pattern of who gets diverticula?
More as people age. Up yo 65% of people have them at age 80.
Most common part colon for diverticulosis?
The sigmoid colon.
5 factors contributing to diverticulosis?
Diet Anatomic weakness Increased intraluminal pressure Disordered motility Neurotransmitters
Review: On what side of the colon do diverticula develop?
Where the vasa recta penetrate the circular muscle layer.
Why might diverticula be more likely to develop in the sigmoid colon?
Smaller radius -> higher pressure.
How does diverticulosis start?
Elastin deposition -> thickened taenia coli.
What kind of collagen gets deposited in diverticulosis? What effect does this have?
Type III Collagen.
This causes increased rigidity and inability to accomodate pressure.
What role does segmentation play in forming diverticula?
Causes focal areas of high pressure -> outpouching.
What might be wrong with motility in diverticulosis?
Increased segmental contractile activity; i.e. higher spikes of pressure.
4 neurotransmitter changes in diverticulosis? Net effect?
Increased 5-HT. Increased ACh. Decreased NO. Decreased vasoactive intestinal peptide. Net effect: increased motility and increased colonic pressure.
3 factors that contribute to developing symptoms from diverticula?
Diet (low fiber, high fat).
Lack of physical activty.
Obesity.
3 types of diverticular disease?
Diverticulitis (acute or chronic).
SCAD
SUDD
What is SCAD?
Segmental colitis associated with diverticulosis.
What is SUDD?
Symptomatic uncomplicated diverticular disease.
-persistant GI symptoms from the diverticulosis without macroscopic colitis or diverticulitis.
What are 3 bad outcomes of diverticulitis?
Perforation leading to..
Obstruction
Fistula
Peritonitis
4 areas of overlap between IBS and diverticular disease?
Low grade inflammation.
Alterations in gut microbiome (fecal stasis -> alterations?).
Abnormal colon motility.
Visceral hypersensitivity.
What’s the deal with diverticular bleeding?
These things tend to form where blood vessels penetrate the colon… leaving a vulnerable blood vessel hanging out on the surface of the diverticulum.
