Irritable bowel syndrome (IBS) is a functional bowel disorder that is common, affecting around 20% of patients presenting to outpatient departments. IBS symptoms are not due to any underlying pathological cause, but rather are influenced by factors like altered gut motility or secretion in response to stimuli, hypersensitivity of the gut, and dysregulation of the brain-gut axis associated with greater stress reactivity. Diagnosis is based on Rome II criteria of abdominal pain relieved by defecation and changes in stool frequency or form occurring for at least 3 days per month over the past 3 months. Treatment focuses on education, diet, exercise, antispasmodics, laxatives, antidepressants, and psychotherapy depending on

1. IBS
Irritable bowel syndrome,
a functional bowel disorder

2. IBS
Common in OPD ~20%
Common in young/middle-aged
A positive clinical diagnosis

3. Pathophysiology
 Symptoms of IBS are not pathological
 Factors that affect symptoms are-
 Altered gut reactivity- motility or secretion-
in response to luminal/environmental stimuli
 Hypersensitive gut,
with enhanced visceral perception/pain
 Dysregulation of brain-gut axis,
associated with greater stress reactivity

4. Symptoms
 Chronic abdominal pain/discomfort
 Bloating or distension of abdomen- ‘gas’
 Altered bowel habits- constipation or diarrhea
 Feeling of incomplete evacuation
 Symptoms relieved by bowel movements
 Associated gastro-esophageal reflux, ill-
defined bodyaches, depression/anxiety
 No organic cause

5. Rome II diagnostic criteria
 At least 3 days/month x last 3 months
of abdominal pain/discomfort relieved
with defecation, with change in frequency or
form of stool
 Cumulative symptoms-
 Abnormal stool frequency- <3/week or >3/day
 Abnormal stool form- hard or loose
 Abnormal stool passage- urgency, straining, tenesmus
 Passage of mucus
 Bloating or abdominal distension

6. Warning symptoms/signs
 Old age
 Blood in stool
 Persistent, severe pain
 Fever
 Vomiting
 Dehydration
 Weight loss
 Pallor or anemia
 Abnormal abdominal examination/LNE
 Acute presentation

7. Investigations
Only if required, based on
presence of warning
symptoms/signs

8. Treatment
 Based on nature & severity of
symptoms and functional impairment
 Education & reassurance
 Fiber in diet & exercise
 Pain- antispasmodics
 Constipation- Tegaserod- 5-HT4 agonist (withdrawn),
laxatives-Lactulose
 Diarrhea- Alosetron- 5-HT3 antagonist, Loperamide
 Psychotherapy
 Co-morbid psychiatric illness- TCA or SSRI