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Flashcards in 27 Inflammatory Bowel Syndrome Deck (16):
1

Irritable bowel syndrome (IBS)

  • frequency
  • ?
  • presentations and etiologies
  • response to medical therapy
  • epidemiology

  • most common gastrointestinal diagnosis in American and Western Europe.
  • functional bowel disease,
    • there is an abnormality of function (motility or pain sensitivity), but not a clear anatomic or physiologic problem.
    • collection of conditions which respond to a variety of therapies
  • many different presentations and probably several etiologies;
  • feeble response to medical therapy may result from a failure to address the underlying pathophysiology, including a significant psychological component.
  • Epidemiology
    • most common reason for gastroenterology office visits in the US
    • Women are twice as likely as men to have IBS.
    • similar across ethnic groups.
    • first presentation tends to be under the age of 50 years

2

Making a Diagnosis

  • characterized by
  • IBS symptoms fall into four general categories which may have different pathophysiology:

  • characterized by
    • abdominal pain and a change in stool habits.
    • no typical abnormal findings on histology, imaging, endoscopy, or blood work.
    • diagnosis of exclusion,
      • all routine testing is normal.
    • The diagnosis is clinical and based upon a collection of symptoms.
    • Individual symptoms, such as abdominal pain and loose stools are not specific for IBS. 
  • IBS symptoms fall into four general categories which may have different pathophysiology:
    • Diarrhea predominant (D-IBS)
    • Constipation predominant (C-IBS)
    • Alternating diarrhea-constipation (A-IBS)
    • Normal bowel movements

3

Diagnostic Criteria for IBS:
Manning and ROME Criteria

  • There are several different diagnostic criteria for IBS
  • Manning Criteria
  • ROME Criteria

  • There are several different diagnostic criteria for IBS
    • The Manning criteria can be, but rarely are used, in clinical practice
    • The Rome criteria are mostly used to maintain a standard definition of IBS for clinical trials
    • In clinical practice, there are many patients that do not meet these criteria, but still have IBS or something similar
  • Manning Criteria: The more criteria that are met reflect a more accurate diagnosis of IBS (standard threshold of 3):
    • Pain relieved by defecation
    • More frequent stools with the onset of pain
    • Looser stools with the onset of pain
    • Visible abdominal distention
    • Sense of Incomplete evacuation
  • ROME Criteria: Recurrent abdominal pain (or discomfort) at least three days per month for three months associated with at least two of the following:
    • Improvement with defecation
    • Onset associated with a change in frequency of stool
    • Onset associated with a change in form of stool

4

Diagnostic Criteria for IBS:
Clinical and Historical Characteristics (p.18)

  • The diagnosis of IBS is primarily/
  • common clinical characteristics:
  • historical characteristics that are helpful in the diagnosis of IBS:

  • The diagnosis of IBS is primarily a clinical diagnosis based upon the typical presentation of symptoms and signs. 
  • common clinical characteristics:
    • Abdominal pain in any location, but more often below the umbilicus.
    • Bloating which is often worse after meals
    • Improvement in bloating and abdominal pain after a bowel movement
    • Symptoms exacerbated by stress
    • Other GI symptoms: dyspepsia (stomach upset), heartburn, early satiety
    • Non-GI symptoms: Urinary and sexual difficulty, fibromyalgia
    • Diarrhea>>constipation>>alternating diarrhea and constipation or neither
    • Depression or anxiety
    • History of sexual, physical, or emotional abuse
  • historical characteristics that are helpful in the diagnosis of IBS:
    • Abdominal pain/bloating relieved by defecation
    • Abdominal pain associated with change in stool consistency
    • Psychological distress (anxiety and depression)
    • History of physical, sexual, or emotional abuse
    • Symptoms beginning after a diarrheal illness
    • Affects young men and women

5

Diagnostic Criteria for IBS

  • The physical exam
  • It is important to consider or exclude certain common diseases which may have symptoms similar to D-IBS. These include:

  • The physical exam is rarely remarkable for any abnormality except for diffuse abdominal tenderness.
  • It is important to consider or exclude certain common diseases which may have symptoms similar to D-IBS. These include:
    • Colon cancer
    • Inflammatory bowel disease
    • Microscopic colitis
    • Celiac disease
    • Lactose intolerance
    • Tropical sprue
    • Small bowel bacterial overgrowth
    • Bile salt malabsorption
    • Hyperthyroidism

6

Diagnostic Criteria for IBS:
Initial evaluations to consider

  • D-IBS
  • C-IBS
  • If the patient does not respond to one or more IBS therapies/
  • Pathophysiology

  • D-IBS
    • Blood count and electrolytes
    • Stool for ova & parasites (Giardia)
    • 24 hour stool collection
    • Celiac testing
    • Breath testing (small bowel bacterial overgrowth/Fructose intolerance)
    • Colonoscopy with biopsies (microscopic colitis/inflammatory bowel disease)
    • Lactose challenge (lactose intolerance)
    • Thyroid levels (hyperthyroidism)
  • C-IBS
    • Blood count and electrolytes
    • Calcium
    • Thyroid levels (hypothyroidism)
  • If the patient does not respond to one or more IBS therapies then further studies depending on diarrhea or constipation predominance should be considered.
  • Pathophysiology: IBS is most likely a combination of causes which leads to disease

7

Pathophysiology:
Small intestinal bacterial overgrowth (SIBO)

  • symptoms
  • how many IBS patients have SIBO
  • effective in the treatment of SIBO and (to a lesser degree) IBS

  • The symptoms of SIBO are similar to the symptoms of IBS
  • up to two-thirds of IBS patients have SIBO based on a hydrogen breath test.
  • Antibiotics, such as ciprofloxacin, metronidazole, neomycin, and rifaximin, have all been effective in the treatment of SIBO and (to a lesser degree) IBS.

8

Pathophysiology:
Visceral hypersensitivity (p.22)

  • Approximately two-thirds of IBS patients have/
  • They experience/

  • Approximately two-thirds of IBS patients have enhanced pain sensitivity to experimental gut stimulation.
  • They experience greater radiation of pain to stimuli and increased peripheral or central sensitization.

9

Pathophysiology:
Inflammation

  • 10-25% of IBS patients report that their symptoms began/
  • There are increased levels of/
  • patients with severe IBS had/

  • 10-25% of IBS patients report that their symptoms began after a diarrheal illness.
  • There are increased levels of pro-inflammatory cytokines including tumor necrosis factor-α (TNF- α) and interleukin-6 (IL-6).
  • patients with severe IBS had increased lymphocyte infiltration of the myenteric plexus.

10

Pathophysiology:
Dysmotility:
Findings which may explain some of the IBS symptoms

  • Gastric
  • Small Intestine
  • Colon
  • Rectum

  • Gastric
    • Delayed gastric emptying
  • Small Intestine
    • D-IBS – Increased motility
    • Poor intestine-intestinal inhibitory reflex
  • Colon
    • D-IBS - Increased colonic motility
    • C-IBS - Decrease colonic motility
  • Rectum
    • Lower rectal compliance and/or higher rectal tension

11

Pathophysiology:
Post-infectious (p.26)

  • In approximately 25% of patients, IBS symptoms commence/
  • Possible causes of post-infectious IBS include:

  • In approximately 25% of patients, IBS symptoms commence after a diarrheal illness.
  • Possible causes of post-infectious IBS include:
    • Organism invasion and damage of the mucosal nerves.
    • An increase in enteroendocrine cells, T lymphocytes and gut permeability.
    • Increased healthcare seeking behavior in patients with pre-existing IBS who suffer a diarrheal illness.

12

Pathophysiology:
Psychologic dysfunction

  • strong psychological component to IBS.
  • A possible explanation for the neuropsychological component of IBS

  • strong psychological component to IBS.
    • Psychologic and psychiatric disease is common in patients who seek medical care for IBS.
    • Depression, anxiety, phobias, and somatization are common.
    • perhaps it is the psychologic dysfunction which affects how experience IBS, but does not cause the symptoms.
    • Patients with IBS are more likely than controls to have suffered physical, sexual, or emotional abuse.
  • A possible explanation for the neuropsychological component of IBS is that corticotropin releasing factor (CRF), a mediator in the stress response, causes anxiety and depression.
    • Administration of CRF increases abdominal pain and colonic motility more so in patients with IBS than controls.

13

Pathophysiology:
Non-celiac gluten sensitivity (NCGS)

  • NCGS has emerged as an explanation for/
  • patients who reported improved symptoms on a gluten free diet at baseline that were reintroduced gluten or placebo demonstrated/

  • NCGS has emerged as an explanation for the symptoms experienced by patients who test negative for celiac serologies with normal duodenal biopsies, but have an apparent exacerbation with gluten intake.
  • patients who reported improved symptoms on a gluten free diet at baseline that were reintroduced gluten or placebo demonstrated a symptomatic benefit of the gluten free diet.

14

Pathophysiology:
Fructose (FODMAP) intolerance

  • acronym
  • ?
  • include/
  • contained in/

  • Fermentable, Oligo-, Di-, Mono-saccharides And Polyols (FODMAPs)
  • short chain carbohydrates which are poorly absorbed in the small intestine and fermented in the colon causing distention and GI symptoms in certain people.
  • include fructose (fructans), galactose (galactans), disaccharides (lactose), monosaccharides (fructose), and sugar alcohols (polyols) such as sorbitol and mannitol.
  • contained in many fruits, vegetables and legumes.

15

Treatment

  • There are three components to successful treatment of IBS.
  • importance of the therapeutic relationship
  • Patient education is particularly important in IBS.

  • There are three components to successful treatment of IBS.
    • Therapeutic Relationship
    • Patient Education
    • Medical Therapy
  • importance of the therapeutic relationship
    • significant psychological component to IBS.
    • Patients have often seen many physicians and have been dismissed as “crazy”, told “it is all in your head” or treated dismissively.
    • Many patients have anxiety, depression, and poorly managed stress, which contributes to their symptoms.
    • A reassuring relationship with the physician can have a significant effect on patient quality of life and response to therapy.
  • Patient education is particularly important in IBS.
    • a patient’s understanding of the physician’s approach instills confidence in the patient.
    • reassure the patient that IBS is not life threatening since some patients have significant anxiety and fear that they may have cancer or another disease.

16

Symptom based therapy

  • Diarrhea
  • Constipation
  • Pain

  • Diarrhea
    • Antidiarrheals
    • Smooth muscle relaxants
    • Antibiotics
    • TCAs
    • Alosatron
  • Constipation
    • Fiber
    • Laxatives
    • Antibiotics
    • Lubiprostone
    • Tegasarod
  • Pain
    • Smooth muscle relaxants
    • TCAs
    • Antibiotics
    • SSRIs