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IRRITABLE BOWEL SYNDROME - a patient's guide
Dr Ishy Maharaj - Gastroenterologist
What is it?
The irritable bowel syndrome is the most common gastrointestinal
disease in clinical practice. It is a condition characterised
by abdominal pain or discomfort, change in stool frequency
or consistency, abdominal distention, the sensation of incomplete
evacuation and the passage of mucus. It can vary in severity
from being a minor infrequent disorder in some to being
a disabling disorder in others.
While it is by no means a life-threatening condition it
can cause a great deal of distress in some individuals and
also poses a significant challenge to doctors involved in
the management of these individuals.
IBS is a worldwide disorder with a prevalence in the community
of around 20%. There is a remarkable consistency in the
prevalence of this disorder in the United States of America,
United Kingdom, Europe and New Zealand. However, most patients
with the symptoms of IBS (60 to 75%) do not consult a doctor.
Individuals with the irritable bowel syndrome constitutes
up to 50% of the referrals to gastroenterologists. IBS is
more common in females with the female to male predominance
being 2:1. IBS is most common in the 20 to 40 year age group.
Symptoms begin before the age of 35 in 50% of patients
and 40% of patients are aged between 35 and 50. IBS is recognised
in children and many patients can trace the onset of the
symptoms back to their childhood. Onset in old age is rare
and it is important in this age group to exclude more serious
conditions.
What is the cause?
The cause of IBS is not known. No structural, biochemical
or infectious etiology has been found. Possibilities include
genetic, hormonal, dietary, infective and psychosocial factors
have been considered but none have been proven to be the
underlying cause. However, some of these factors can influence
symptoms in individuals with IBS. It is known that certain
foods such as legumes are not tolerated well by patients
with IBS. It has been shown that gastrointestinal symptoms
including abdominal pain, nausea and diarrhoea are more
likely to be reported during menses in women with IBS. Psychosocial
factors play an important role in IBS.
As mentioned previously, the greater majority of patients
with IBS do not present to a doctor. It has been shown that
patients not seeking medical attention are not psychologically
different from healthy subjects. Therefore, while psychosocial
factors do not cause the IBS symptoms, they can influence
how symptomatic patients respond. It is not clear whether
those who do seek medical attention actually have more severe
symptoms because their psychological disturbances effect
pain sensation or whether they experience similar symptoms
but report them as more severe. It is not uncommon for the
ongoing symptoms of IBS to start after a gastrointestinal
infection, for example, after contracting travellers' diarrhoea.
Although the infection resolves either spontaneously or
with treatment, the individual is left with the chronic
symptoms of IBS. It is possible that these individuals have
the potential for IBS which is triggered by infection.
The fundamental disturbance thought to be responsible
for IBS symptoms are two fold. Firstly, the IBS is thought
to be the result of abnormal contractions (motility) of
the large intestine (colon). Contractions lead to spasms
in the colon, causing abdominal pain, diarrhoea or constipation.
Secondly, it is felt that the intestines of individuals
with IBS have increased sensitivity to normal events that
occur in the bowel such as spasm and distension. These individuals
experience abdominal pain and bloating sensations when the
level of colon contractions may not be excessive. It is
well know that air insufflation or balloon distention of
the rectum, sigmoid colon or small intestine causes abdominal
pain in IBS patients at volumes usually not painful in normal
subjects. It is not know whether this is as a result of
fundamental defects in the nerve cells of the bowel wall
or whether the underlying problem is an altered perception
of pain by the brain.
It was previously thought that the motility disturbance
and hypersensitivity to pain was limited to the large intestine
(colon), hence IBS was previously referred to as spastic
colon. It is now known as IBS is a more generalised disorder
of the gastrointestinal tract. For example, involvement
of the oesophagus is not uncommon and can result in non-cardiac
chest pain, heart burn, difficulty in swallowing (dysphagia)
and a feeling of a lump in the throat (globus sensation).
Abnormal contractions have also been demonstrated in the
stomach, small intestine and gallbladder; the latter giving
rise to symptoms similar to the pain of gallstones. There
is also a higher incidence of gynaecological and urological
symptoms in patients with the IBS. These include increased
urinary frequency, dysuria (pain on passing urine), dyspareunia
(pain during intercourse) and inhibited sexual desire. These
individuals also have more generalised symptoms such as
fatigue and lethargy.
What are the symptoms?
A diagnosis of IBS is based on a careful and detailed
history to identify characteristic positive symptoms which
on the one hand identify IBS and on the other, exclude conditions
that mimic it, selected laboratory investigations and sigmoidoscopy
(an instrument for looking up the lower bowel). In some
individuals further testing (e.g. colonoscopy) will be required
to exclude other disorders.
The history should include a detailed history of the abdominal
pain and its association with food and bowel motion. Careful
description of bowel frequency, consistency and volume should
be elicited. Associated symptoms such as flatulence, bloating
and gastro-oesophageal reflux should be looked for if the
patient has not already volunteered this history. A careful
dietary history is essential, including use of caffeine
beverages, or foods and beverages sweetened with fructose
or sorbitol which may cause diarrhoea, bloating or cramps.
It is important that psychosocial factors be specifically
looked for, including the reason for the consultation (e.g.
fear of cancer). The typical symptoms of IBS which can often
enable a positive diagnosis to be made are very well outlined
in what is referred to as the Rome Criteria:
At least three months of continuous or recurrent symptoms
of:
1) Abdominal pain or discomfort that is -
Relieved with defaecation; and/or
Associated with a change in frequency of stool; and -
2) Two or more of the following, at least on 1/4 of occasions
or days:
Altered stool frequency (more than 3 a day or less than
3 per week)
Altered stool form (lumpy, hard or loose/watery stool)
Altered stool passage (straining, urgency, or a feeling
of incomplete evacuation.
Passage of mucus; and/or
Bloating or feeling of abdominal distension.
Patients with constipation-predominant IBS may have many
days or weeks of constipation interrupted with brief episodes
of diarrhoea. Constipation, which at first is episodic,
eventually may become continuous and increasingly intractable
to laxatives and later to enemas. Stools are usually hard
and variably described as pellets, marble-like, or small
hard balls. On the other hand, stool calibre may be narrow
(pencil-thin or ribbon-like).
Pain may become more severe with increasing duration and
severity of constipation. In half of patients evacuation
leads to relief of pain but frequently there is a sensation
of incomplete evacuation leading to repeated attempts at
defaecation with minimal or no success. Several hours may
be devoted to this process before some relief is obtained.
Diarrhoea attributable to IBS usually consists of small
volumes of loose stool. Evacuation is often preceded by
extreme urgency, occurring typically in the morning or after
meals. The initial movement may be normal in consistency
then rapidly followed by a softer, unformed stool and then
by increasingly loose stools. Abdominal pain preceding the
movement is commonly relieved by defaecation, albeit sometimes
only briefly. Diarrhoea following a meal is another feature
of IBS. This usually correlates with the quantity rather
than the type of food. This diarrhoea is sometimes explosive
because it consists of a mixture of gas and fluid; and it
is usually associated with extreme urgency or pain. The
stools in individuals with diarrhoea may be described as
loose, mushy or watery.
Pain is variously described as vague, bloating, crampy,
burning, dull, aching, knife-like, sharp or steady. Acute
episodes of severe, sharp, knife-like pain may be superimposed
on a constant or intermittent background of dull aching
pain. The pain is more often localised in the left lower
abdomen than at any other site and more often in the lower
abdomen than in the upper abdomen. It is experienced more
often in several sites than in one site. Rectal pain may
be present and ranges from mildly annoying to extremely
disturbing. Pain is often precipitated by meals and relieved
by defaecation. Rarely does the pain awaken the patient
from sleep.
Bloating or perceived abdominal distension is a common
complaint in IBS, belching and excessive flatus is also
commonly reported. Increased stool mucus is often seen in
IBS, it can be clear or whitish.
The physical examination in IBS patients is generally
unremarkable. Abdominal tenderness, often in the left lower
abdomen may be elicited. The doctor should look out for
possible psychological disorders. Furthermore, "alarm" symptoms
which point to more serious underlying conditions should
be looked for. These include onset in old age, steady progressive
course, frequent awakening by symptoms, fever, weight loss
and rectal bleeding.
All patients with IBS should have a few basic tests done.
These include a full blood count, ESR, stool examination
for occult blood and a sigmoidoscopy. In addition, specific
tests may be required to exclude disorders such as parasitic
infection, inflammatory bowel disease and lactose intolerance
(stool examination for ova and parasites and pus cells,
colonoscopy or small bowel enema and lactose tolerance test).
In individuals with associated upper-abdominal symptoms,
gastroscopy may be indicated.
Conditions which mimic IBS include lactose intolerance,
laxative abuse, gallbladder disease, inflammatory bowel
disease (ulcerative colitis and Crohn's disease), parasitic
infections (such as Giardia or amebiasis), diverticular
disease and more importantly colonic malignancy, especially
in the older patients. Side effects of drugs may always
be kept in mind as the possible cause of symptoms resembling
IBS. An enquiry should also be made about the use of "over
the counter" drugs which some patients may not think is
necessary to mention. Others may intentionally avoid disclosing
drugs they may have become dependant on.
What is the treatment?
The diagnosis of IBS heralds a long-term relationship
between doctor and patient. It is very important that a
positive doctor/patient relationship is established at the
onset. A positive outcome is most likely when the doctor
is non-judgmental, establishes realistic expectations and
consistent limits, encourages the patient's understanding
of the illness and involves the patient in treatment decisions.
The patient needs to be reassured of the benign nature of
the illness and the excellent long-term prognosis. It should
be emphasised that although there is no cure for IBS, there
are steps that both the doctor and patient can take to improve
the symptoms.
Initial recommendations generally focus on dietary modifications.
These include avoidance of dairy products, food beverages
or medications containing fructose or sorbitol, excessive
caffeine, or gas-forming food such as legumes. Many IBS
patients believe that their symptoms are caused by specific
foods and may often unnecessarily restrict what they eat.
Fibre supplements can often be recommended regardless
of the presenting complaint but are particularly useful
if constipation is the predominant symptom. Natural fibre
such as wheat bran, wholemeal and mixed grain bread, porridge,
weetbix, muesli and other bran cereals, wholemeal flour,
vegetables and raw fruit are inexpensive but a significant
number of patients complain that a high-fibre diet aggravates
symptoms, particularly bloating and distension. Certain
agents such as psylium compounds (e.g. Metamucil, Granocol,
Isogel, Konsyl Orange, Metamucil Orange, Mucilax and Normacol)
tend to produce less gas and are preferred in the treatment
of IBS. Because these agents absorb water, they prevent
excessive dehydration of stool as well as excessive liquidity.
Therefore, they may be effective for both constipation and
diarrhoea. These agents should be taken with meals so that
they become part of the stool as it is formed. Patients
are advised to eat slowly, not to chew gum or drink carbonated
beverages and to avoid artificial sweeteners such a sorbitol
and fructose.
While some patients will improve with the simple measures
as outlined above, others will require additional medication
for their symptoms. There is no single medication that will
benefit all patients with this disorder. Therefore, management
will be very individual.
As pain is often a major symptom in IBS, antispasmodic
agents such as Colofac, Buscopan and Merbentyl are commonly
used. These reduce the abdominal cramps and to a lesser
degree the bloating. Anti-diarrhoeal agents (Lomotil, Imodium
and related drugs) are used where diarrhoea is a prominent
symptom.
Antidepressants are also very useful in the treatment
of IBS. Beside their obvious benefit in those with underlying
anxiety and depression, they also reduce intestinal spasm
and are also known to raise the pain threshold.
A high-fibre diet and agents such as Metamucil are beneficial
in patients with constipation-dominant IBS. Intermittent
use of agents such as Lactulose, Senekot, Coloxyl with Senna
etc. may be required. Care needs to be taken that the patient
does not become dependent on laxatives. As IBS is a chronic
disorder, habit forming drugs such as codeine-containing
compounds should be avoided for fear of the patient developing
drug dependence.
Psychotherapy is indicated as a treatment for patients
with concomitant psychiatric illness and for patients who
have not responded to the measures outlined above. In one
trial where patients were given psychotherapy, it was shown
that those who received this treatment did significantly
better than those given conventional medical treatment only.
Furthermore, those patients treated with psychotherapy showed
a significant decrease in their need for medical consultation
and investigation.
Presently, trials are being undertaken on drugs which
relieve abdominal bloating, increase tolerance to colonic
distension and reduce rectal sensitivity. Initial results
look promising.
While IBS can be a disabling condition, long-term prognosis
is very good. This condition does not lead to more serious
conditions of the bowel such as inflammatory bowel disease
or bowel cancer.
Conclusion:
The IBS is a rather paradoxical disorder. While on the
one hand it can be an ongoing chronic disabling condition,
on the other hand it has an excellent prognosis. A successful
outcome will depend on an understanding of the condition
and a doctor who can empathise about this often distressing
but fortunately benign disorder.
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