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Medically, irritable bowel syndrome (IBS) is known by a
variety of other terms: spastic colon, spastic colitis, mucous
colitis and nervous or functional bowel. Usually, it is a
disorder of the large intestine (colon), although other parts of
the intestinal tract-even up to the stomach----can be affected.
The colon, the last five feet of the intestine, serves two
functions in the body. First, it dehydrates and stores the stool
so that, normally, a well-formed soft stool occurs. Second, it
quietly propels the stool from the right side over to the rectum,
storing it there until it can be evacuated. This movement occurs
by rhythmic contractions of the colon.
 When IBS occurs, the colon
does not contract normally. Instead, it seems to contract in a
disorganized, at times violent, manner. The contractions may be
terribly exaggerated and sustained, lasting for prolonged periods
of time. One area of the colon may contract with no regard to
another. At other times, there may be little bowel activity at
all. These abnormal contractions result in changing bowel
patterns with constipation being most common.
A second major feature of IBS is abdominal discomfort or pain.
This may move around the abdomen rather than remain localized in
one area. These disorganized, exaggerated and painful
contractions lead to certain problems. The pattern of bowel
movements is often altered. Diarrhea may occur, especially after
meals, as the entire colon contracts and moves liquid stool
quickly into the rectum. Or, localized areas of the colon may
remain contracted for a prolonged time. When this occurs, which
often happens in the section of colon just above the rectum, the
stool may be retained for a prolonged period and be squeezed into
small pellets. Excessive water is removed from the stool and it
becomes hard. Also, air may accumulate behind these localized
contractions, causing the bowel to swell. So bloating and
abdominal distress may occur. Some patients see gobs of mucous in
the stool and become concerned. Mucous is a normal secretion of
the bowel, although most of the time it cannot be seen. IBS
patients sometimes produce large amounts of mucous, but this is
not a serious problem. The cause of most IBS symptoms---diarrhea,
constipation, bloating, and abdominal pain-are due to this
abnormal physiology.
IBS Is Not a Disease
Although the symptoms of IBS may be severe, the disorder
itself is not a serious one. There is no actual disease present
in the colon. In fact, an operation performed on the abdomen
would reveal a perfectly normal appearing bowel. Rather, it is a
problem of abnormal function. The condition usually begins in
young people, usually below 40 and often in the teens. The
symptoms may wax and wane, being particularly severe at some
times and absent at others. Over the years, the symptoms tend to
become less intense. IBS is extremely common and is present in
perhaps half the patients that see a specialist in
gastroenterology. It tends to run in families. The disorder does
not lead to cancer. Prolonged contractions of the colon, however,
may lead to diverticulosis, a disorder in which balloon-like
pockets push out from the bowel wall because of excessive,
prolonged contractions.
Causes
While our knowledge is still incomplete about the function and
malfunction of the large bowel, some facts are well-known.
Certain foods, such as coffee, alcohol, spices, raw fruits,
vegetables, and even milk, can cause the colon to malfunction. In
these instances avoidance of these substances is the simplest
treatment. Infections, illnesses and even changes in the weather
somehow can be associated with a flare-up in symptoms. So can the
premenstrual cycle in the female. By far, the most common factor
associated with the symptoms of IBS are the interactions between
the brain and the gut. The bowel has a rich supply of nerves that
are in communication with the brain. Virtually everyone has had,
at one time or another, some alteration in bowel function when
under intense stress, such as before an important athletic event,
school examination, or a family conflict. People with IBS seem to
have an overly sensitive bowel, and perhaps a super abundance of
nerve impulses flowing to the gut, so that the ordinary stresses
and strains of living somehow result in colon malfunction.
These exaggerated contractions can be demonstrated
experimentally by placing pressure, sensing devices in the colon.
Even at rest, with no obvious stress, the pressures tend to be
higher than normal. With the routine interactions of daily
living, these pressures tend to rise dramatically. When an
emotionally charged situation is discussed, they can reach
extreme levels not attained in people without IBS. These symptoms
are due to real physiologic changes in the gut-a gut that tends
to be inherently overly sensitive, and one that overreacts to the
stresses and strains of ordinary living.
Diagnosis
The diagnosis of IBS often can be suspected just by a review
of the patient's medical history. In the end it is a
diagnosis of exclusion; that is, other conditions of the bowel
need to be ruled out before a firm diagnosis of IBS can be made.
A number of diseases of the gut, such as inflammation, cancer,
and infection, can mimic some or all of the IBS symptoms. Certain
medical tests are helpful in making this diagnosis, including
blood, urine and stool exams, x-rays of the intestinal tract and
a lighted tube exam of the lower intestine. This exam is called
endoscopy, sigmoidoscopy or colonoscopy. Additional tests often
are required depending on the specific circumstances in each
case. If the proper medical history is obtained and if other
diseases are ruled out, a firm diagnosis of IBS then can usually
be made.
Treatment
The treatment of IBS is directed to both the gut and the
psyche. The diet requires review, with those foods that aggravate
symptoms being avoided. Current medical thinking about diet has
changed a great deal in recent years. There is good evidence to
suggest that, where tolerated, a high roughage and bran diet is
helpful. This diet can result in larger, softer stools which seem
to reduce the pressures generated in the colon. Large amounts of
beneficial fiber can be obtained by taking over-the-counter
bulking agents such as psyllium mucilloid (Metamucil, Konsyl) or
methylcellulose (Citrucel). As many people have already
discovered, the simple act of eating may, at times, activate the
colon. This action is a normal reflex, although in IBS patients
it tends to be exaggerated. It is sometimes helpful to eat
smaller, more frequent meals to block this reflex. There are
certain medications that help the colon by relaxing the muscles
in the wall of the colon, thereby reducing the bowel pressure.
These drugs are called antispasmodics. Since stress and anxiety
may play a role in these symptoms, it can at times be helpful to
use a mild sedative, often in combination with an antispasmodic.
Physical exercise, too, is helpful. During exercise, the bowel
typically quiets down. If exercise is used regularly and if
physical fitness or conditioning develops, the bowel may tend to
relax even during non-exercise periods. The invigorating effects
of conditioning, of course, extend far beyond the intestine and
can be recommended for general health maintenance. As important
as anything else in controlling IBS is learning stress reduction,
or at least how to control the body's response to stress. It
certainly is well-known that the brain can exert controlling
effects over many organs in the body, including the
intestine.
Summary
Patients with IBS can be assured that nothing serious is wrong
with the bowel. Prevention and treatment may involve a simple
change in certain daily habits, reduction of stressful
situations, eating better and exercising regularly.
Perhaps the most important aspect of treatment is reassurance.
For most patients, just knowing that there is nothing seriously
wrong is the best treatment of all, especially if they can learn
to deal with their symptoms on their own.
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