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In medicine (gastroenterology),
irritable
bowel syndrome (IBS) is a group of
functional bowel disorders which are fairly
common and make up 20–50% of visits to a
specialist.
Symptoms of
Irritable Bowel Syndrome
Symptoms of
IBS are abdominal pain or discomfort
associated with changes in bowel habits in
the absence of any structural abnormality.
Colonic hypersensitivity is a sensitive but
less specific sign of Irritable Bowel Syndrome. Depending on the
kind of discomfort and bowel habits, IBS is
also known as spastic colon, and can be subclassified into diarrhea-predominant
(IBS-D), constipation-predominant (IBS-C)
and Irritable Bowel Syndrome with alternating stool pattern
(IBS-A). Typical is the overlap of Irritable Bowel Syndrome with
chronic pelvic pain (this is probably due to
misdiagnosis by the gynaecologist),
fibromyalgia and
mental disorder.
Diagnosis of IBS
According to
the Rome II consensus conference of the
American Gastroenterological Association and
international medical societies on
functional bowel disorders, the diagnosis of
Irritable Bowel Syndrome can be made when the following criteria
are fulfilled: At least 12 weeks, which need
not be consecutive, in the preceding 12
months of abdominal discomfort or pain that
has 2 of 3 features:
- Relieved
with defecation; and/or
- Onset
associated with a change in frequency of
stool; and/or
- Onset
associated with a change in form
(appearance) of stool. Symptoms that
cumulatively support the diagnosis of IBS
- Abnormal
stool frequency (for research purposes,
“abnormal” may be defined as greater than
3 bowel movements per day and less than 3
bowel movements per week);
- Abnormal
stool form (lumpy/hard or loose/watery
stool);
- Abnormal
stool passage (straining, urgency, or
feeling of incomplete evacuation);
- Passage of
mucus;
- Bloating
or feeling of abdominal distention.
The diagnosis
of a functional bowel disorder always
presumes the absence of a structural or
biochemical explanation for the symptoms.
This has to be excluded carefully via:
-
colonoscopy
-
esophagogastroduodenoscopy (EGD)
- abdominal
ultrasound
- blood
tests: full blood count, liver enzymes,
electrolytes, renal function
- stool
chemistry (e.g. tests for exocrine
pancreas insufficiency and other
malabsorption conditions), stool
microbiology, fecal fat
- H2-tests
for lactose intolerance and fructose
malabsorption
- deep
duodenal biopsy or blood tests for
celiac
disease
A diagnostic
test for Irritable Bowel Syndrome via assessment of
colonic/rectal hypersensitivity using a barostat is currently being discussed.
However, sensitivity and specificity are not
yet high enough to render the method widely
applicable.
Pathophysiology
of IBS
Research on
the etiology of IBS has not yet brought
forth unanimous results. Changes in colonic
motility and immunologic causes have been
discussed. Hypersensitivity of the gut is a
major finding in IBS patients. The
association of IBS with stress is less
clear. Studies have shown that there may be
a correlation between Irritable Bowel Syndrome and prior sexual
or physical abuse.
About 25% of
patients develop symptoms after a hefty
enteritis (partially after use of
antibiotics, see also diarrhea). In these
cases, a prolonged
immune reaction is
currently discussed as pathogenetic. So far,
this is mainly based on experiments in the
animal model.
IBS is widely
regarded as a conglomeration of disorders
with similar symptoms but a different
etiology ("trash can"). As with many other
medical conditions, there is a lot of
speculation about causes, including in the
field of alternative medicine.
IBS Treatment
The most
important therapeutic measure is reassuring
the patient that he has no fatal or
otherwise threatening disease, as this is
the major concern of patients seeking
medical help. Dependent on IBS symptoms,
treatment can consist of dietary advice,
stool softeners and laxatives in
constipation-predominant, and antidiarrheals
(loperamide) in diarrhea-predominant IBS.
The use of antispasmodic drugs is not
encouraged as the therapeutic benefit over
placebo is hardly proven. Newer drugs
include Alosetron and Tegaserod, both of
which are heavily advertised but have only a
limited effect. Psychotherapy is another
treatment option, however many patients
refuse to undertake this. Though not
specifically indicated for Irritable Bowel Syndrome, the use of
antidepressant drugs (e.g. amitriptyline in
a low dosage or an SSRI) to treat the
symptoms is common and has positive effects
for some patients.
Epidemiology
of
Irritable Bowel Syndrome
Point
prevalence is 10 - 20% of the general
population of Western countries with a much
higher lifetime prevalence. Prevalence is
similar in India, Japan and China. Irritable Bowel Syndrome is
less common in Thailand and rural South
African areas. In Western countries, but not
in India or Sri Lanka, females have a
greater risk to develop IBS. |
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However, of the
persons who have symptoms of IBS, only a
proportion seeks medical help. However,
there is not yet a predictor known for who
will seek medical help and who will not.
Prognosis of
IBS
Irritable Bowel Syndrome is not
fatal nor is linked to the development of
other serious bowel diseases. However, due
to the chronic pain, discomfort and other
symptoms, work absenteeism, social phobias
and other negative quality-of-life effects
can be common in more serious cases.
Individuals lucky enough to find a
successful treatment for their symptoms can
lead normal lives.
By: The Medical Symptoms
Database
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