Bowel terminology

Your bowel consists of 2 specialised parts, namely the colon and the rectum. The colon is broadly referred to as having 2 halves, the right colon (or right hemicolon) and the left colon (or left hemicolon). The rectum is broadly divided into three parts, the upper, middle and lower thirds. Various parts of the colon have specific names, as shown in the diagram below. Doctors refer to parts of the bowel sometimes according to whether it is the upstream portion ("proximal") or the downstream portion ("distal"). The colon is very variable in its length and in the number of convolutions or bends in the tubing.


What is Ulcerative Colitis?

Ulcerative Colitis (UC) is a disease of the rectum and the colon (otherwise known as the large intestine). It is one of the two conditions that are known as Inflammatory Bowel Diseases – the other being Crohn’s disease. Any medical term that ends in -itis means that there is inflammation or damage to that part of the body. The term ‘colitis’ means that the colon has become inflamed and, if this becomes severe enough, the lining of the colon is actually breached and ulcers may form. The term ‘ulcerative colitis’ can seem confusing as many patients never develop ulcers because the degree of inflammation is not that advanced. It’s best to think of UC as a disease in which there is wide variation in the amount of inflammation so that in mild cases the colon can look almost normal but when the inflammation is bad, the bowel can look very diseased and can contain ulcers. Ulcerative colitis always affects the rectum; sometimes, the inflammation is limited just to the rectum – this is known as proctitis. However, the inflammation can involve a variable length of the colon. When the whole colon is affected, this is called pan-colitis or total colitis.

Who gets Ulcerative Colitis?

The disease usually begins between the ages of 15 and 30 although it can appear at any age. It seems that men and women are equally likely to be affected. About 100,000 people in the UK have ulcerative colitis. It is fairly certain that there is nothing you might have done that could have brought it on. There appears to be a genetic predisposition to UC in some families, as such families may contain more affected relatives than would be expected in "normal" family trees.

What causes Ulcerative Colitis?

We don’t know the cause of ulcerative colitis. Doctors have looked hard to find either an infection or something in the diet that might be causing the disease, but have drawn a blank. For a while it seemed that ulcerative colitis might be one of those diseases where the body seemed to be attacking itself. We now think that very unlikely, but there is no doubt that something must be causing damage to the lining of the large intestine. Most doctors now think the cause of UC relates to how patients react to the apparently harmless bacteria that everyone has in their colon. In most people, the bacteria that live in the colon do not cause any damage and indeed can be quite useful. They are sometimes known as ‘friendly’ bacteria. However, patients with ulcerative colitis don’t see them as being at all friendly and when the lining of the large intestine goes into battle with these bacteria, the result is that the inflammation starts. An enormous research effort is under way to find out why patients with ulcerative colitis appear to react badly to bacteria that don’t normally cause any harm.

What are the symptoms?

The three most common symptoms of UC are diarrhoea, bleeding from the back passage and pain in the abdomen. However, symptoms do vary from one patient to the next, so many people do not have all three of these together. For example, some patients may just notice that they pass blood when they open their bowels. Others may not have diarrhoea but feel rather constipated. To a certain extent, the symptoms depend on how much inflammation there is and how much of the colon is affected by the disease. For some people, the symptoms can seem just a nuisance. For others, the condition can really interfere with day-to-day life which becomes organized around visits to the toilet. It is not only just the number of times this can happen each day but the hurry in which some patients need a toilet can also be extremely distressing. As symptoms are often at their worst in the morning, this can mean the start of the day can be quite an ordeal. Some patients pass considerable quantities of mucus when they open their bowels. Others can be greatly troubled by wind. Many patients can just feel tired, not their usual self and they (or their family and friends) notice they have become just plain irritable.

How is Ulcerative Colitis diagnosed?

Doctors use three separate steps to come to a precise diagnosis. Firstly, they will listen to your symptoms and ask you questions about your health. This is called ‘taking your history’. Secondly they will want to examine you to see if they can detect any ‘signs’ that something is wrong. For example, they may notice that you are unusually pale (which might suggest you are anaemic) or, perhaps, you seem rather tender when the doctor presses gently on your tummy (which can be a sign of inflammation in the colon). Thirdly, they will probably ask you to undergo some tests.

If your doctor thinks you might have ulcerative colitis, you will probably be asked to have tests of your blood, your motions and your intestines. Blood tests will show if you are anaemic and whether your illness has caused the level of protein to fall. In general, the greater the degree of anaemia and the lower the protein level, the more severe the inflammation is likely to be.
Doctors also use special blood tests called ESR and CRP to give a measure of the degree of inflammation. You may be asked to give small samples of your bowel motions so as to be sure there are no signs of any bowel infection. The most important investigation is to look directly at the lining of the large intestine. Sometimes the doctor will choose to carry out such an examination in the out-patient clinic. This is known as sigmoidoscopy and has the convenience of you not having to take any special preparations beforehand as the doctor will only look at the rectum and perhaps the lowest part of the sigmoid colon. However, sooner or later, the doctor will want to see more of your bowel and the best way to do this is by the technique of colonoscopy. A colonoscope is a tube which is long enough but sufficiently flexible to be passed through your back passage along the whole length of the colon. You will be asked to follow a special diet and also to take some quite powerful laxatives just before the test to make sure the bowel is entirely empty. You will be offered an injection beforehand to minimise any discomfort that might be caused – but an anaesthetic is only needed very rarely. It is usually possible to see all of the rectum and the colon and it is likely that the doctor will take some biopsies (tiny pieces of the lining of the bowel) to study under a microscope after the procedure has finished. A colonoscopy will confirm the diagnosis of ulcerative colitis and provide detailed information on the extent and severity of inflammation in the intestine. Biopsies are often used to confirm the diagnosis.

What is the treatment?

The cause of ulcerative colitis is not known. This has two important implications for treatment which patients should understand. Firstly, until the cause is discovered it is most unlikely that there will be a medicine that will cure the condition. Secondly, all treatments available at present are directed towards reducing the amount of inflammation in the bowel. Fortunately, for most patients with UC, medicines prove effective although it is possible that your treatment may need to be varied to find the drugs that work best for you. Your doctors will firstly try to find a treatment that will bring the disease under control. Then they will work on finding a treatment to keep you that way. Bringing ulcerative colitis under control Almost always, the choice of treatment will depend on the extent and severity of the inflammation within the large bowel. If the inflammation is confined to the rectum (‘proctitis’), it is quite possible the doctor will recommend a medication that you will need to insert into the rectum through the back passage. Although the thought of this can be unpleasant, it can be helpful to appreciate that giving your treatment this way does mean that the therapy is really directed right against the inflamed part of your bowel. Treatment can be given as suppositories or as enemas. Enemas can also be useful if the disease involves more of the large bowel than just the rectum alone, but if the inflammation in the bowel is extensive enough to affect more than half of the colon, it is likely that you will be prescribed tablets to take by mouth.

What drugs are available?

The anti-inflammatory drugs include aminosalicylates in milder cases and steroids if the inflammation is more severe. There are a variety of aminosalicylates (such as mesalazine) and your doctors will choose the preparation they feel is best for you. They are usually extremely safe to use. Steroids (such as prednisolone) are more powerful but doctors are rather reluctant for patients to take these drugs for more than a few weeks at a time because of the risk of side-effects. However, most patients do get better with these treatments. How might a relapse be prevented? Your doctor will discuss alternative ways of preventing relapse. Quite often, aminosalicylates are helpful. If possible, doctors try to avoid giving patients with UC steroids in the long term because of sideeffects. As an alternative, the possibility of taking azathioprine may be discussed with you. This calms down the immune system and, although only weakly effective against active disease, it has proved most useful in preventing relapses. This drug does need close monitoring in the first few weeks of treatment in order to detect side-effects although most people do not have any problems when they take it.

What will happen if treatment with medicines fails?

Doctors try hard to control UC with drugs and medicines. But if these don’t help, or should you become very unwell, you may be offered admission to hospital. If the disease still fails to respond to treatment, it is likely that a surgical operation to remove the colon (called a colectomy) will be considered. Although surgery can seem a drastic step, it does cure the disease (if you don’t have a colon, you can’t have colitis). In former times, colectomy used to mean needing a bag to wear on your tummy. Nowadays, it is usually possible to remove the diseased colon and rectum and then construct a pouch of small intestine that acts very much like the rectum. So no need for a bag.

Can Ulcerative Colitis cause complications?

A small number of patients do have complications that relate to UC in their skin, eyes, joints or liver as a result of their disease. When you attend the hospital, you will be monitored to see if any of these complications do develop so that they can be treated. You may have heard that patients with UC run an increased risk of getting bowel cancer. The bad news is that this is true; the good news is that bowel cancer is still an uncommon complication of the disease and that your doctor will keep an eye on your bowel (quite literally by colonoscopy at regular intervals) to detect pre-malignant changes in the lining of the bowel at a stage well before cancer has yet developed.



         Crohn's ulcers in the gut                    "Snail track" ulcers            "Skip lesions" of abnormal small                                                                                                            intestine lining

Bowel and intestinal terminology

Your Intestine is sometimes referred to as your "small" intestine whilst the bowel (colon and rectum) is sometimes referred to as your "large" intestine.

The small intestine consists of three parts: duodenum, then jejunum and finally ileum. When speaking of the end of the small intestine, we sometimes call it the "terminal" ileum.

The large intestine consists of 2 specialised parts, namely the colon and the rectum. The colon is broadly referred to as having 2 halves, the right colon (or right hemicolon) and the left colon (or left hemicolon). The rectum is broadly divided into three sections, the upper, middle and lower thirds. Various parts of the colon have specific names, as shown in the diagram below. Doctors refer to parts of the bowel sometimes according to whether it is the upstream portion ("proximal") or the downstream portion ("distal"). The colon is very variable in its length and in the number of convolutions or bends in the tubing.


   Colon (peripherally) and small intestine (centrally) as viewed from the patient's left side


What is Crohn’s disease? 

Crohn’s disease as one of the types of Inflammatory Bowel Disease. It is a disease that is defined as chronic as it may last for many years. It is a disease that may affect any part of the digestive system from the mouth to the anus but it most usually involves the lower end of the small intestine or the colon and rectum. A variety of symptoms can occur depending on which part of the digestive system is affected. It is a disease that may reappear intermittently with flare-ups between intervals of relative quiessence.

Who gets Crohn’s disease?

Crohn’s Disease most commonly affects young adults, but it can affect teenagers and even younger children. A second peak in incidence occurs adults the age of 60. Men and women are equally affected. I affects about 1 in 1000 people. Crohn’s disease might run in families i.e. there may be first or second degree relatives who have similarly been affected. Certain ethnic groups are more at risk than others e.g. Ashkenazim and Iranians. Approximately one fifth of Crohn’s patients have a relative affected by this disease.

What causes Crohn’s disease?

Crohn’s disease probably results from the immune system in the digestive tract reacting abnormally to bacteria at the surface of the gut. It is likely that this complex system of immunity has an inherited genetic flaw causing it as a number of genes have been identified as abnormal in Crohn’s patients. Aside from the inherited risks, there appears also to be additional risks, the most important of which is smoking. There is no confirmed evidence that diet is implicated in the development of Crohn’s disease.

Where does Crohn’s disease commonly occur?

The most common site for Crohn’s disease is in the last part of the small intestine called the ileum. It may also occur in the first part of the colon called the caecum, near where the appendix grows. In other patients the disease affects the colon, similar to Ulcerative Colitis. A minority of patients have disease active in multiple sites in the digestive system, both the small intestines, the colon and the rectum or anus. Crohn’s disease is also associated sometimes with inflammation in other parts of the body such as inflammation in joints causing arthritis, inflammation in the eye causing uveitis and inflammation in the skin. It is very rare for patients to have Crohn’s disease affecting their mouth, their oesophagus or their stomach.

What are the symptoms of Crohn’s disease?

Symptoms arising from this disease will vary both in intensity and character and they are very much dependent upon which part of the body has been affected. In its commonest and mildest form, Crohn’s disease would cause inflammation in the lining of the intestines. This inflammation is often patchy when mild it causes merely some thickening and rawness of the gut lining. If it progresses, it may form deep ulcers. This disturbance to the lining of the intestines typically results in disturbance to the pattern of bowel motion, typically diarrhoea (loose and frequent stool). When the condition is mild, vague discomfort in the abdomen may occur, particularly after meals. Should the ulcers become very deep and lead to a leakage of the intestinal content out of the gut, this will usually create an abscess, severe pain and a temperature. Symptoms may well sound like appendicitis although the duration is longer than with the latter. When inflammation in the intestine is on-going for some weeks or months the intestines may become thickened to the point that passage of food or waste through the intestine becomes compromised. Such patients report bloating and cramping pain. This may go on to develop into a complete intestinal obstruction in which case vomiting occurs. Inflammation that is chronic often results in consumption of the body’s building materials and/or failure to absorb building materials, leading to weight loss and anaemia.

When Crohn’s disease results in severe inflammation, it is possible for abscesses to develop around the site of inflammation. These abscesses may find their way out of the body to the surface skin, allowing intestinal waste to breach the skin. This is termed a fistula. Fistulae are most commonly found in the skin surrounding the anus, but they can reach vaginal skin in women, the bladder in both sexes and the abdominal wall. When Crohn’s disease affects the lower reaches of the colon and rectum, the inflammation may lead to bleeding into the gut and this blood might be visible mixed in with the stools. Those patients who have non-intestinal Crohn’s disease may present with severe mouth ulcers, difficulty swallowing, indigestion, sore eyes, painful and swollen joints or tender skin rashes. 

How is Crohn’s disease diagnosed?

A careful history and examination is always essential as the symptoms may be subtle, the signs may not be very evident and a comprehensive history such as that of your family members may give clues that an inexperienced doctor will miss. The diagnosis is unlikely to be confirmed by these two steps alone i.e. you are likely to need tests to confirm the diagnosis. Other illnesses such as infectious diarrhoea need to be excluded so a stool sample will be sent off for culture and it will be tested for blood or chemical substances that indicate inflammation is present (faecal calprotectin). Blood tests similarly can be used to exclude other illnesses but the doctor is particularly interested in evidence of anaemia (particularly the iron deficient type) and chemical markers of inflammation (CRP and ESR). It is difficult to describe all the tests that may be required as Crohn’s disease offers such as spectrum of severities and localities for symptoms. Often you will be required to undergo an endoscopy procedure, a camera procedure performed to examine the digestive system from within. These procedures include OGD (oesophagogastroduodenoscopy, or gastroscopy for short, an inspection of the upper digestive system), flexible sigmoidoscopy (inspection of the rectum and lower colon) and colonoscopy (inspection of the rectum and the whole colon). These procedures may allow direct inspection of the areas of inflammation and biopsies can be taken from these areas to confirm the diagnosis. If the small intestines and is thought to be affected, most cameras cannot reach into this area and some form of radiological investigation will be required instead. These may include a CT scan or an MRI scan, usually performed with a drink containing dye that will outline the intestinal cavities. When Crohn’s disease affects intimate areas such as the genitals, the anus or the mouth, an examination may have to be performed whilst the patient is asleep under anaesthetic. 

How is Crohn’s disease treated?

The management of Crohn’s disease falls between two different branches of medicine, Gastroenterology and Colorectal Surgery. A gastroenterologist is a specialist physician who manages diseases of the digestive system whilst a colorectal surgeon manages these diseases too when they require a surgical solution. The aim of Crohn’s disease treatment is to reduce the inflammation in the intestine sufficiently to allow normal digestive function to occur. Crohn’s patients often need the help of the dietician to ensure that they are getting adequate calories and food constituents to ensure health. There is no specific diet for Crohn’s disease, but often a reduction in fibre in indigestible food will help. This is known as a “low residue” diet. Very rarely do patients require specialised liquid diets containing formula feeds, known as “elemental” or “polymeric” diets.

A variety of medications are available to settle inflammation and the surrounding infection caused by Crohn’s disease. Antibiotics such as metronidazole are used to reduce the bacteria that drive the inflammation or to treat abscesses. A group of drugs called aminosalicylates are often used, often with good effect. These drugs are related to the aspirin that is commonly used and they settle inflammation from within the gut. More powerful suppressors of the immune system may sometimes be required. These include steroids (prednisolone and hydrocortisone), immune suppressors or immune modulators (azathioprine, 6-mercaptopurine, methotrexate) and biological therapy (infliximab). A gastroenterologist is very familiar with these drugs and would advise any patient in great detail about them.

Surgery remains an important part of the management of Crohn’s disease. It is rarely needed from the outset but rather when medical management with drugs has been tried and failed. Some patients respond well to medication but develop symptoms from unwanted side-effects of the medication and thus choose surgery so that they can be spared from these. When Crohn’s disease affects a very small portion or isolated segment of the intestine, surgery may be a reasonable first line of treatment that is preferable to medical therapy for some patients. When complications from Crohn’s disease occur e.g. fistula, abscess, perforation, obstruction etc, colorectal surgeons are required to address this. Your surgeon would very carefully advise you of the role of surgery, the effects that this will have upon you and any side-effects or consequences of the surgery that has been necessary.