Irritable Bowel Syndrome (IBS) Definition, Causes, Diagnosis and Treatment

Irritable Bowel Syndrome (IBS) is defined as a functional bowel disorder in absence of structural pathology.


The etiology is uncertain:-
(1) Psychological disturbances e.g. anxiety and somatisation are evident.
(2) Altered GI motility.
(3) Visceral hypersensitivity
(4) Luminal factors: eg. abnormality in gut flora.

Clinical Picture of IBS:

(long history with long symptom-free intervals).
1. Recurrent abdominal pain: it is classically situated in the left iliac fossa.
2. The pain is decreased by defecation or passing flatus.
3. There is constipation or diarrhea with feeling of incomplete evacuation.
4. The stools may be ribbon like with passage of mucus.
5. Abdominal distention is extremely common.
6. Abnormal stool passage e.g. straining or urgency.
7. Tenderness over the sigmoid colon.
8. Features of irritable person usually present.

Diagnostic Criteria of IBS ( Rome  Criteria ):

Abdominal discomfort or pain that has two of three of the following features:
Relieved with defecation and/Or:
Onset associated with a change in frequency of stool, and/or:
Onset associated with a change in form or appearance of stool.
Abnormal stool frequency i.e. > 3/ day and < 3/ week.
Abnormal stool form (hard, loose, watery, lumpy).

Non GI features of Irritable Bowel Syndrome:

- Dysmenorrhoea.
- Premenstrual tension.
- Headache.
- Bad breath.
- Unpleasant taste in the mouth.
-  Poor sleeping and Fatigue.
- Urinary symptoms e.g. frequency, urgency.

Factors that can trigger IBS:

GI infection.
Antibiotic therapy.
Psychological stress.
Mood disorders.
Eating disorders.
Pelvic surgery.
No positive findings .
- Recurrent pain in the right hypochondrium is usually not due to gall bladder
disease, but to the irritable bowel syndrome.
- Recurrent pain in the right iliac fossa is not due to chronic appendicitis, but to
the irritable bowel syndrome.

Treatment of Irritable Bowel Syndrome

1. Patients must be reassured of the benign nature of the condition.
2. A high fiber diet and bran are helpful.
3. Smooth muscle relaxants for pain e.g. Mebeverine.
4. Selective serotonin reuptake inhibitor paroxetine (Seroxat) in constipation
5. Tricyclic antidepressant e.g. amytriptyline (Tryptizole) 10-25 mg or
nortiptyline 75mg in diarrhea-predominant.
6. Tegaserod which is serotonin receptor agonist it activates serotonin
receptors in GIT (zelmac), 6mg/12hr, it can be used also in constipation -

Other GI symptoms suggestive of Psycho-somatic (Functional) disorders:

Nausea alone.
Abdominal bloating.
Vomiting alone.
Chronic right hypochondrial pain.
Chronic left iliac fossa pain.
Irritable Bowel Syndrome (IBS) Definition, Causes, Diagnosis and Treatment
Dr.Tamer Mobarak


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