Chapter17: INTESTINES:Irritable Bowel Syndrome

Question 1

What is Irritable bowel syndrome (IBS)?

Answer 1

is characterized by chronic, relapsing abdominal pain, bloating, and changes in bowel habits. [91]

Despite very real symptoms, the gross and microscopic
evaluation is normal in most IBS patients.

Thus, the diagnosis depends on clinical symptoms

Question 2

What is the pathogenesis of IBS?

Answer 2

The pathogenesis of IBS remains poorly defined, although there is clearly an interplay between psychologic stressors, diet, and abnormal GI motility.

Data showing disturbances of intestinal
motility and enteric sensory function suggest that impairment of signaling in the brain-gut axis
contributes to IBS.

A small subgroup of IBS patients also relate onset to a bout of infectious gastroenteritis, suggesting an immune or neuroimmune contribution.

Question 3

What is the peak prevalence of IBS?

Answer 3

The peak prevalence of IBS is between 20 and 40 years of age, and there is a significant
female predominance. .

Question 4

IBS is presently diagnosed using clinical criteria that require what?

Answer 4

• the occurrence of abdominal pain or discomfort at least 3 days per month over 3 months
• ,improvement with defecation, and a
• change in stool frequency or form.

Many patients also report fibromyalgia or other chronic pain disorders, visceral hypersensitivity, backache, headache, urinary symptoms, dyspareunia,
lethargy, and depression.

Variability in diagnostic criteria makes it difficult to establish the incidence, but most authors report a prevalence in developed countries of between 5% and
10%.

Question 5

What conditions will IBS be excluded?

Answer 5

In those with:

• diarrhea
• , microscopic colitis,
• celiac disease,
• giardiasis,
• lactose intolerance,
• small bowel bacterial overgrowth,
• bile salt malabsorption,
• colon cancer , and
• inflammatory bowel disease must be excluded (although IBS is common in inflammatory bowel

disease patients).

IBS is not associated with serious long-term sequelae, but affected patients
may undergo unnecessary abdominal surgery due to chronic pain and their ability to function
socially may be compromised. The prognosis of IBS is most closely related to symptom
duration, with longer duration correlating with reduced likelihood of improvement. Ongoing life
stressors also reduce the chance of symptom resolution. Consistent with the uncertain
mechanisms of disease, diverse treatments are used including psychotherapy, dietary fiber
supplementation, tricyclic antidepressants, selective serotonin reuptake inhibitors, probiotics,
and antibiotics. In addition, a chloride channel agonist may provide benefit in a subset of
patients whose primary manifestation is constipation

Question 6

IBS is not associated with serious long-term sequelae, but affected patients may undergo unnecessary abdominal surgery due to what?

Answer 6

due to chronic pain and their ability to function
socially may be compromised

Question 7

What is the prognosis of IBS?

Answer 7

The prognosis of IBS is most closely related to symptom duration, with longer duration correlating with reduced likelihood of improvement.

Ongoing life stressors also reduce the chance of symptom resolution.

Consistent with the uncertain
mechanisms of disease, _diverse treatments are used including psychotherapy, dietary fiber
supplementation, tricyclic antidepressants, selective serotonin reuptake inhibitors, probiotics,
and antibiotics._

In addition, a chloride channel agonist may provide benefit in a subset of patients whose primary manifestation is constipation.

Question 8

What provides benefit in patiets whose primary manifestation of IBS is constipation?

Answer 8

chloride channel agonist may provide benefit in a subset of patients whose primary manifestation is constipation.