The gut (gastrointestinal tract) is the long tube that starts at the
mouth and ends at the anus. When we eat, food passes down the
oesophagus (gullet), into the stomach, and then into the small
intestine.
The
small intestine has three sections - the duodenum, jejunum and ileum.
The small intestine is where food is digested and absorbed into the
bloodstream. The structure of the gut then changes to become the large
intestine (colon and rectum, sometimes called the large bowel).
The
colon absorbs water, and contains food that has not been digested, such
as fibre. This is passed into the last part of the large intestine,
where it is stored as faeces. Faeces (motions or stools) are then
passed out of the anus into the toilet.
Who gets Crohn's disease?
Crohn's disease
affects about 1 in 1500 people. It can develop at any age but most
commonly starts between the ages of 15 and 30. It affects women
slightly more often than men.
Which part of the gut is affected in Crohn's disease?
In
Crohn's disease, one or more patches of inflammation develop in parts
of the gut. Any part of the gut can be affected. However, the most
common site for the disease to first start is the last part of the
small intestine (the ileum). The ileum is affected in about half of
cases. Other parts of the small intestine and the colon are also
commonly affected. The mouth, gullet and stomach are affected much less
commonly.
A patch of inflammation may be small, or spread quite
a distance along part of the gut. Several patches of inflammation may
develop along the gut, with normal sections of gut in between. In about
3 in 10 cases, the inflammation occurs just in the small intestine. In
about 2 in 10 cases the inflammation occurs just in the colon. In a
number of cases, the inflammation occurs in different places in the gut.
What causes Crohn's disease?
The
cause is not known. About 3 in 20 people with Crohn's disease have a
close relative who also has it. This means there may be some genetic
factor. However, other factors such as a bacterium or virus (germ) may
be involved. One theory is that a germ may trigger the immune system to
cause inflammation in parts of the gut in people who are genetically
prone to develop the disease.
Crohn's disease has become more
common in recent years, but the reason for this is not known. It is
about three times more common than average in smokers. Also, on
average, smokers tend to have more severe disease than non-smokers.
What are the symptoms during a flare-up of Crohn's disease?
Symptoms
are due to inflammation in the wall of the affected parts of the gut.
When the disease flares up, the inflammation may cause one or more of
the following.
-
Diarrhoea is the most common first
symptom. It can vary from mild to severe. The diarrhoea may be mixed
with mucus, pus or blood. An urgency to get to the toilet is common. A
feeling of wanting to go to the toilet but with nothing to pass is also
common (tenesmus).
-
Pain occurs in about 7 in 10 cases. The site of the pain
depends on which part of the gut is affected. The last part of the
small intestine (ileum) is the commonest site. Therefore, a common area
of pain is the lower right side of the abdomen. When Crohn's disease
first develops it is sometimes mistaken for appendicitis. The severity
of pain can vary from person to person. Also, a sudden change or
worsening of pain may indicate a complication (see below).
-
Weight loss that is not intentional is another common symptom.
-
Ulcers. An ulcer is a raw area of the lining of the gut which may bleed. You may see blood when you pass stools (motions or faeces).
-
Generally feeling unwell which may include loss of appetite, fever, and tiredness.
-
Anaemia may occur if you lose a lot of blood.
-
Mouth ulcers are common.
-
Anal fissures may occur. These are painful 'cracks' in the
skin of the anus. Skin tags (small fleshy wart-like lumps) may also
appear around the anus.
The symptoms can vary and depend on which part(s) of the gut are affected. For example:
- You may not have diarrhoea if the disease is just in the small intestine.
- A persistent pain in the abdomen without any other symptoms may be
due to a small patch of Crohn's disease in the small intestine.
- A severe flare-up can make you generally very ill.
- If large parts of the gut are affected, you may not absorb food
well, and you may become deficient in vitamins and other nutrients.
Other symptoms
Other parts of the body are
affected in some people in addition to the gut. These include:
inflammation and pain of some joints (arthritis); skin rashes;
inflammation of the eye (uveitis); liver inflammation. These problems
can cause various symptoms. It is not clear why these other problems
occur. The immune system may trigger inflammation in other parts of the
body when there is inflammation in the gut. These other problems tend
to go when the gut symptoms settle, but not always.
How does Crohn's disease progress?
Crohn's
disease is a chronic, relapsing condition. Chronic means that it is
ongoing. Relapsing means that there are times when symptoms flare-up
(relapse), and times when there are few or no symptoms (remission).
The
severity of symptoms, and how frequently they occur, varies from person
to person. The first episode (flare-up) of symptoms is often the worst.
What are the possible complications of Crohn's disease?
Complications
may occur, particularly if flare-ups are frequent or severe. These
include the following which often need treatment with surgery.
-
Stricture.
This is a narrowing of part of the gut. It is due to scar tissue that
may form in the wall of an inflamed part of the gut. A stricture can
cause difficulty in food passing through (a 'blockage'). This leads to
pain and vomiting.
-
Perforation. This is a small hole that forms in the wall of
the gut. The contents of the gut can then leak out and cause infection
or an abscess inside the abdomen. This can be serious and
life-threatening.
-
Fistula. This is when the inflammation causes a channel to
form between two parts of the body. For example, a fistula may form
between a part of the small intestine with part of the colon. Fistulas
can also form between part of the gut and other organs such as the
bladder or uterus (womb). The contents of the gut may then leak into
these other organs. A perianal fistula sometimes develops. This is a
fistula that goes from the anus or rectum and opens onto the skin near
to the anus.
-
Cancer. People with Crohn's disease have a small increased
risk of developing cancer of the colon compared to the risk of the
general population.
-
Osteoporosis ('thinning of the bones'). The increased risk of this is related to the poor absorption of food that occurs in some people with severe Crohn's disease.
How is Crohn's disease diagnosed?
Depending
on where the symptoms arise from, various tests may be done to confirm
the diagnosis, and determine how much of the gut is affected. For
example, if you have symptoms coming from the colon or ileum, then a
doctor may look inside the colon and ileum using a special flexible
telescope called a colonoscope. The colonoscope is passed through the
anus, up into the colon, and a little further into the ileum. See
separate leaflet called 'Colonoscopy' for more detail.
The
typical appearance of the inside lining of the colon or ileum suggests
Crohn's disease. Biopsies (small samples) of the lining of various
parts of the colon and ileum are usually taken. These are looked at
under a microscope. The typical pattern of the cells may confirm the
diagnosis.
If you have symptoms coming from the upper part of
the gut, then a doctor may suggest a gastroscopy (endoscopy). This is
where a thin, flexible telescope is passed down the oesophagus into the
stomach. This allows a doctor or nurse to look inside. See separate
leaflet called 'Gastroscopy (Endoscopy)' for more detail.
A
special X-ray of the large intestine (barium enema) or small intestine
(barium meal) may be advised. Barium coats the lining of the gut and
shows up as white on X-ray films. Typical patterns on the films show
which parts of the gut are affected. More sophisticated tests such as
an MRI or CT scan may be needed if the diagnosis is in doubt, or if
complications are suspected.
Also, blood tests are helpful from
time to time to assess the level of inflammation within the gut, to
check for anaemia and other deficiencies, and to assess your general
wellbeing.
What are the aims of treatment?
There are two main aspects of treatment:
- When a flare-up develops - a main aim is to clear symptoms. That is, to cause a remission of the disease.
- When a flare up has settled - a main aim is to prevent any further flare-ups of symptoms. That is, to keep you in remission.
What are the treatment options for a flare-up of Crohn's disease?
The
treatment advised can depend on various factors. For example, the
severity of the symptoms, the site or sites of the inflammation in the
gut, whether associated problems have developed such as eye
inflammation, and what treatments worked best for you in the past.
Treatment decisions can become complex, and a specialist will usually
advise. Options that may be considered include the following:
No treatment
This is an option for some
people who have mild symptoms. There is a chance that the symptoms will
settle on their own. If symptoms get worse, then decisions about
medication can be reviewed.
A course of steroids (corticosteroids)
The
two commonly used steroids for Crohn's disease are budesonide and
prednisolone. In about 7 in 10 cases, symptoms are much improved within
four weeks of starting steroids. The dose is reduced gradually, and
then stopped once symptoms ease. A course of steroids for a few weeks
is normally safe. Steroids are not usually continued once a flare-up
has settled. The aim is to treat any flare-ups, but to keep the total
amount of steroid treatment over the years as low as possible.
Although
steroid tablets are commonly used, a steroid enema or suppository is
also an option for a mild flare-up confined to the lower large
intestine. Steroid injections directly into a vein may be required for
a severe flare-up.
Immunosuppressant drugs
Newer powerful drugs
have become available in recent years that suppress the immune system.
These have made a bit impact on the treatment of Crohn's disease in
recent years. They tend to be divided into two groups:
Immunomodulators.
These are drugs that modify and suppress the immune system. They
include azathioprine, mercaptopurine, and methotrexate. They tend to be
used in more severe cases, and in those where steroid treatment has not
helped much.
Biological therapies. These are genetically
engineered proteins such as special antibodies called monoclonal
antibodies. These can target specific chemicals of the immune system
involved in the inflammation process. In Crohn’s disease, a chemical
called cytokine tumour necrosis factor (TNF-alpha) is involved in the
inflammation process. Drugs called infliximab and adalimumab (which are
really manufactured antibodies) block the action of this chemical and
therefore suppress the disease activity. Treatment with infliximab or
adalimumab is an option in some cases. For example, in people who do
not respond to steroid medication or to immunomodulators, or in certain
situations causing severe symptoms. These drugs need to be given
directly into a vein but then typically persist in the body for many
weeks with long lasting effects.
Aminosalicylate drugs
These are only
sometimes used for Crohn's disease (unlike in ulcerative colitis, a
related condition, where they are used more commonly). They include
mesalazine, ofsalazine, balsalazide and sulfasalazine. The exact way
these drugs work is not clear but they are thought to counter the way
inflammation develops in Crohn's disease.The active ingredient of each
of these drugs is 5-aminosalicylic acid, but each drug is different in
how the active ingredient is released or activated in the gut.
Mesalazine is the most commonly used. Each of these drugs comes in
different brand names and different preparations such as oral tablets,
sachets or suspension, liquid or foam enemas, or suppositories. The
type of preparation (for example, tablets or enemas) may depend on the
main site of the inflammation in the gut.
Antibiotics
May need to be added to other
treatments if infective complications are suspected. For example, if
you develop an infected fistula such as an infected perianal fistula.
Dietary treatments
A very strict liquid diet
that contains basic proteins and other nutrients has been found to help
in some cases. This is called an 'elemental' diet and is mainly used in
children. A flare-up can settle within four weeks in some people who
have this diet. After this, a normal diet is gradually re-started. It
is not clear why this treatment works. It may have some effect of
'resting' the gut. This may be an alternative for some people when
medication has not worked so well, or has caused bad side-effects.
However, it is a controversial treatment.
Surgery
An operation to remove a severely
affected section of gut may be needed if other treatments do not work.
The gut is cut above and below the affected part which is removed. The
two ends are then joined up. Surgery is also usually needed to treat
complications such as fistulas, strictures, and abscesses.
General measures
- Iron tablets may be prescribed if you develop anaemia.
- Vitamins and other nutrient supplements may be needed if a large part of the gut is affected and food is poorly absorbed.
- Nutritional support such as 'dripping' nutrients directly into a vein (parenteral nutrition) may be needed in severe cases.
- Painkillers may be needed for a while during flare-ups.
- Hospital admission for intravenous fluids (drip) and intensive treatment may be needed if you have a severe flare-up.
What are the treatment options to prevent flare-ups of symptoms?
Once
a flare-up has settled, without treatment, on average there is about a
1 in 2 chance that another flare-up will develop within a year. Certain
factors increase the likelihood of more severe and more frequent
flare-ups. For example, the severity of the first flare-up, the extent
of the disease in your gut, you age, and the extent of treatment needed
to control the initial flare-up. For some people it may not be
worthwhile taking regular medication if flare-ups are not frequent, or
are mild, and respond well to treatment when they occur. For others,
medication to prevent flare-ups can make a big difference to quality of
life.
The treatment options that may be considered to prevent
flare-ups (which in medical language is 'to maintain remission')
include the following:
- Regular mesalazine (mentioned
earlier). This is less commonly used than previously as it is not
considered effective in many cases. However, it still has a role in
some cases, particularly to 'maintain remission' after having a part of
your gut removed as a treatment for a flare-up.
- A regular dose of an immunomodulator (described earlier). This is becoming more widely used as a treatment to prevent flare-ups.
- A regular dose of a biological therapy (described earlier). For
example, an infusion of infliximab every eight weeks. This may be used
in selected cases where flare-ups are severe, and other treatments have
not worked so well.
Each of the above treatments increases the chance of remaining
free of flare-ups, but they do not always work. There is a balance
between the likely benefits, and the possible side-effects that occur
in some people. Your doctor will advise about the pros and cons of
long-term medication, and which medication is best for your
circumstance. Note: steroid medication is not generally used long-term
to prevent flare-ups.
For smokers, giving up smoking may reduce
the number and severity of flare-ups. It would always be wise to try
and give up smoking. There are treatments that can help smokers to
quit. Ask your doctor for advice on this.
Newer treatments
The treatment of Crohn's
disease is an evolving field. Various new drugs are under investigation
and may change the treatment options over the next ten years or so.
Crohn's disease and pregnancy
If you have
Crohn's disease and are planning to become pregnant it is advised that
you discuss this in advance with your doctor. For example, you may need
extra folate supplements, and certain drugs which may be used for
Crohn's disease such methotrexate must not be used during pregnancy.
What is the outlook (prognosis)?
The outlook
is variable. It depends on which part or parts of the gut are affected,
and how often and how severe the flare-ups are. Without treatment:
- About 3 in 20 people with Crohn's disease have frequent and/or severe flare-ups.
- A few people would have just one or two flare-ups in their life, but for most of their life have no symptoms.
- Most people would fall somewhere in between, have flare-ups from time to time, but can have long spells without symptoms.
Sometimes a severe flare-up is life-threatening and a small
number of people die as a result of a serious complication such as a
perforated gut.
Modern immunosuppressant drugs has made a big
impact in recent years. Recent reports suggest that about 15 in 20
people with Crohn's disease remain in work 10 years after diagnosis.
So, this means that in the majority of cases, with the help of
treatment, the disease is manageable enough to maintain a near normal
life. However, the burden of the disease can be heavy for some people
with severe disease.
Up to 8 in 10 people with Crohn's disease
require surgery at some stage in their life for a complication. In
about half of people with Crohn's disease, surgery is needed within the
first 10 years of developing the disease. The most common reason for
surgery is to remove a stricture that has formed. Some people need
several operations in their lifetime. If you develop Crohn's disease as
a young adult, on average you can expect to have 2-4 operations in your
lifetime. However, there is some evidence that the rate of surgery is
coming down, probably due to the more modern drug treatments now
available.
What is inflammatory bowel disease?
When
doctors talk of 'inflammatory bowel disease' they usually mean people
who either have Crohn's disease or ulcerative colitis. Both of these
conditions can cause inflammation of the colon and rectum (large bowel
or large intestine) with similar symptoms such as bloody diarrhoea,
etc. Although these conditions are similar, and treatments are similar,
there are differences. For example, the inflammation of ulcerative
colitis tends to be just in the inner lining of the gut, whereas the
inflammation of Crohn's disease can spread through the whole wall of
the gut. Also, ulcerative colitis only affects the colon and rectum
whereas Crohn's disease can affect any part of the gut. See separate
leaflet called 'Ulcerative Colitis' for more detail.
However,
about 1 in 20 people with 'inflammatory bowel disease' affecting just
the colon cannot be classified as either Crohn's disease or ulcerative
colitis because they have some features of both conditions. This is
sometimes called indeterminate colitis.
Note: inflammatory bowel
disease is sometimes shortened to 'IBD'. This is not the same is 'IBS'
which is short for irritable bowel syndrome - a very different disease.
Disclaimer: This article is for information only and should not
be used for the diagnosis or treatment of medical conditions. EMIS and
PiP have used all reasonable care in compiling the information but make
no warranty as to its accuracy. Consult a doctor or other health care
professional for diagnosis and treatment of medical conditions.
© EMIS and PiP 2008 Reviewed: 26 Aug 2008
